diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index a4791cb7f..0cf54830f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -281,6 +281,10 @@ if( NOT NO_FMOD )
 	if( FMOD_INCLUDE_DIR )
 		message( STATUS "FMOD include files found at ${FMOD_INCLUDE_DIR}" )
 		include_directories( "${FMOD_INCLUDE_DIR}" )
+		
+		if( EXISTS "${FMOD_INCLUDE_DIR}/fmod_common.h" )
+			set( FMOD_STUDIO YES )
+		endif()
 	else()
 		message( STATUS "Could not find FMOD include files" )
 		set( NO_FMOD ON )
@@ -1481,7 +1485,16 @@ endif()
 
 if( MSVC )
 	option( ZDOOM_GENERATE_MAPFILE "Generate .map file for debugging." OFF )
-	set( LINKERSTUFF "/MANIFEST:NO /DELAYLOAD:\"fmodex${X64}.dll\"" )
+	set( LINKERSTUFF "/MANIFEST:NO" )
+
+	if( NOT NO_FMOD )
+		if( FMOD_STUDIO )
+			set( LINKERSTUFF "${LINKERSTUFF} /DELAYLOAD:\"fmod${X64}.dll\"" )
+		else()
+			set( LINKERSTUFF "${LINKERSTUFF} /DELAYLOAD:\"fmodex${X64}.dll\"" )
+		endif()
+	endif()
+
 	if( ZDOOM_GENERATE_MAPFILE )
 		set( LINKERSTUFF "${LINKERSTUFF} /MAP" )
 	endif()
@@ -1521,17 +1534,23 @@ if( APPLE )
 		MACOSX_BUNDLE_INFO_PLIST "${CMAKE_CURRENT_SOURCE_DIR}/posix/osx/zdoom-info.plist" )
 
 	if( NOT NO_FMOD )
+		if( FMOD_STUDIO )
+			set( FMOD_DYLIB libfmod.dylib )
+		else()
+			set( FMOD_DYLIB libfmodex.dylib )
+		endif()
+
 		# Fix fmod link so that it can be found in the app bundle.
 		find_program( OTOOL otool HINTS "/usr/bin" "${OSX_DEVELOPER_ROOT}/usr/bin" )
 		find_program( INSTALL_NAME_TOOL install_name_tool HINTS "/usr/bin" "${OSX_DEVELOPER_ROOT}/usr/bin" )
 		execute_process( COMMAND "${OTOOL}" -L "${FMOD_LIBRARY}"
-			COMMAND grep "libfmodex.dylib (compat"
+			COMMAND grep "${FMOD_DYLIB} (compat"
 			COMMAND head -n1
 			COMMAND awk "{print $1}"
 			OUTPUT_VARIABLE FMOD_LINK
 			OUTPUT_STRIP_TRAILING_WHITESPACE )
 		add_custom_command( TARGET zdoom POST_BUILD
-			COMMAND "${INSTALL_NAME_TOOL}" -change "${FMOD_LINK}" @executable_path/../Frameworks/libfmodex.dylib "$<TARGET_FILE:zdoom>"
+			COMMAND "${INSTALL_NAME_TOOL}" -change "${FMOD_LINK}" @executable_path/../Frameworks/${FMOD_DYLIB} "$<TARGET_FILE:zdoom>"
 			COMMENT "Relinking FMOD Ex" )
 	endif()
 endif()
diff --git a/src/c_console.cpp b/src/c_console.cpp
index 08f850675..086861229 100644
--- a/src/c_console.cpp
+++ b/src/c_console.cpp
@@ -811,8 +811,8 @@ static void C_DrawNotifyText ()
 						DTA_KeepRatio, true,
 						DTA_AlphaF, alpha, TAG_DONE);
 				else
-					screen->DrawText (SmallFont, color, (screen->GetWidth() / active_con_scaletext() -
-						SmallFont->StringWidth (NotifyStrings[i].Text))/ active_con_scaletext(),
+					screen->DrawText (SmallFont, color, (screen->GetWidth() -
+						SmallFont->StringWidth (NotifyStrings[i].Text) * active_con_scaletext()) / 2 / active_con_scaletext(),
 						line, NotifyStrings[i].Text,
 						DTA_VirtualWidth, screen->GetWidth() / active_con_scaletext(),
 						DTA_VirtualHeight, screen->GetHeight() / active_con_scaletext(),
diff --git a/src/g_shared/sbarinfo_commands.cpp b/src/g_shared/sbarinfo_commands.cpp
index a9fac2ee1..b7827f6bd 100644
--- a/src/g_shared/sbarinfo_commands.cpp
+++ b/src/g_shared/sbarinfo_commands.cpp
@@ -1914,7 +1914,7 @@ class CommandAspectRatio : public SBarInfoCommandFlowControl
 		{
 			SBarInfoCommandFlowControl::Tick(block, statusBar, hudChanged);
 
-			SetTruth(ratioMap[CheckRatio(screen->GetWidth(), screen->GetHeight())] == ratio, block, statusBar);
+			SetTruth(ratioMap[FindRatio()] == ratio, block, statusBar);
 		}
 	protected:
 		enum Ratio
@@ -1931,6 +1931,37 @@ class CommandAspectRatio : public SBarInfoCommandFlowControl
 		static Ratio	ratioMap[5];
 
 		Ratio			ratio;
+
+	private:
+		int FindRatio()
+		{
+			float aspect = ActiveRatio(screen->GetWidth(), screen->GetHeight());
+
+			static std::pair<float, int> ratioTypes[] =
+			{
+				{ 21 / 9.0f , ASPECTRATIO_16_9 },
+				{ 16 / 9.0f , ASPECTRATIO_16_9 },
+				{ 17 / 10.0f , ASPECTRATIO_17_10 },
+				{ 16 / 10.0f , ASPECTRATIO_16_10 },
+				{ 4 / 3.0f , ASPECTRATIO_4_3 },
+				{ 5 / 4.0f , ASPECTRATIO_5_4 },
+				{ 0.0f, 0 }
+			};
+
+			int ratio = ratioTypes[0].second;
+			float distance = fabs(ratioTypes[0].first - aspect);
+			for (int i = 1; ratioTypes[i].first != 0.0f; i++)
+			{
+				float d = fabs(ratioTypes[i].first - aspect);
+				if (d < distance)
+				{
+					ratio = ratioTypes[i].second;
+					distance = d;
+				}
+			}
+
+			return ratio;
+		}
 };
 CommandAspectRatio::Ratio CommandAspectRatio::ratioMap[5] = {ASPECTRATIO_4_3,ASPECTRATIO_16_9,ASPECTRATIO_16_10,ASPECTRATIO_16_10,ASPECTRATIO_5_4};
 
diff --git a/src/g_shared/shared_hud.cpp b/src/g_shared/shared_hud.cpp
index 25a88cb35..e40233def 100644
--- a/src/g_shared/shared_hud.cpp
+++ b/src/g_shared/shared_hud.cpp
@@ -1108,13 +1108,13 @@ void DrawHUD()
 		}
 		else 
 		{
-			if (WidescreenRatio == 4)
+			if (CheckRatio(SCREENWIDTH, SCREENHEIGHT) == 4)
 			{
-				hudheight = hudwidth * 30 / BaseRatioSizes[WidescreenRatio][3];	// BaseRatioSizes is inverted for this mode
+				hudheight = hudwidth * 30 / AspectMultiplier(WidescreenRatio);	// BaseRatioSizes is inverted for this mode
 			}
 			else
 			{
-				hudheight = hudwidth * 30 / (48*48/BaseRatioSizes[WidescreenRatio][3]);
+				hudheight = hudwidth * 30 / (48*48/AspectMultiplier(WidescreenRatio));
 			}
 		}
 	}
diff --git a/src/g_shared/shared_sbar.cpp b/src/g_shared/shared_sbar.cpp
index 4631a99aa..3c41d18ca 100644
--- a/src/g_shared/shared_sbar.cpp
+++ b/src/g_shared/shared_sbar.cpp
@@ -299,14 +299,15 @@ void DBaseStatusBar::SetScaled (bool scale, bool force)
 	{
 		ST_X = 0;
 		ST_Y = VirticalResolution - RelTop;
-		if (CheckRatio(SCREENWIDTH, SCREENHEIGHT) != 4)
+		float aspect = ActiveRatio(SCREENWIDTH, SCREENHEIGHT);
+		if (aspect >= 1.3f)
 		{ // Normal resolution
 			::ST_Y = Scale (ST_Y, SCREENHEIGHT, VirticalResolution);
 		}
 		else
 		{ // 5:4 resolution
-			::ST_Y = Scale(ST_Y - VirticalResolution/2, SCREENHEIGHT*3, Scale(VirticalResolution, BaseRatioSizes[4][1], 200)) + SCREENHEIGHT/2
-				+ (SCREENHEIGHT - SCREENHEIGHT * BaseRatioSizes[4][3] / 48) / 2;
+			::ST_Y = Scale(ST_Y - VirticalResolution/2, SCREENHEIGHT*3, Scale(VirticalResolution, AspectBaseHeight(aspect), 200)) + SCREENHEIGHT/2
+				+ (SCREENHEIGHT - SCREENHEIGHT * AspectMultiplier(aspect) / 48) / 2;
 		}
 		Displacement = 0;
 	}
@@ -1035,10 +1036,10 @@ void DBaseStatusBar::DrSmallNumberOuter (int val, int x, int y, bool center) con
 
 void DBaseStatusBar::RefreshBackground () const
 {
-	int x, x2, y, ratio;
+	int x, x2, y;
 
-	ratio = CheckRatio (SCREENWIDTH, SCREENHEIGHT);
-	x = (!IsRatioWidescreen(ratio) || !Scaled) ? ST_X : SCREENWIDTH*(48-BaseRatioSizes[ratio][3])/(48*2);
+	float ratio = ActiveRatio (SCREENWIDTH, SCREENHEIGHT);
+	x = (ratio < 1.5f || !Scaled) ? ST_X : SCREENWIDTH*(48-AspectMultiplier(ratio))/(48*2);
 	y = x == ST_X && x > 0 ? ST_Y : ::ST_Y;
 
 	if(!CompleteBorder)
@@ -1058,8 +1059,8 @@ void DBaseStatusBar::RefreshBackground () const
 	{
 		if(!CompleteBorder)
 		{
-			x2 = !IsRatioWidescreen(ratio) || !Scaled ? ST_X+HorizontalResolution :
-				SCREENWIDTH - (SCREENWIDTH*(48-BaseRatioSizes[ratio][3])+48*2-1)/(48*2);
+			x2 = ratio < 1.5f || !Scaled ? ST_X+HorizontalResolution :
+				SCREENWIDTH - (SCREENWIDTH*(48-AspectMultiplier(ratio))+48*2-1)/(48*2);
 		}
 		else
 		{
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 0564addc8..cd859c1f0 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -120,7 +120,7 @@ angle_t FGLRenderer::FrustumAngle()
 
 	// ok, this is a gross hack that barely works...
 	// but at least it doesn't overestimate too much...
-	double floatangle=2.0+(45.0+((tilt/1.9)))*mCurrentFoV*48.0/BaseRatioSizes[WidescreenRatio][3]/90.0;
+	double floatangle=2.0+(45.0+((tilt/1.9)))*mCurrentFoV*48.0/AspectMultiplier(WidescreenRatio)/90.0;
 	angle_t a1 = DAngle(floatangle).BAMs();
 	if (a1>=ANGLE_180) return 0xffffffff;
 	return a1;
@@ -915,14 +915,10 @@ void FGLRenderer::RenderView (player_t* player)
 	NoInterpolateView = saved_niv;
 
 
-	// I stopped using BaseRatioSizes here because the information there wasn't well presented.
-	//							4:3				16:9		16:10		17:10		5:4
-	static float ratios[]={1.333333f, 1.777777f, 1.6f, 1.7f, 1.25f, 1.7f, 2.333333f};
-
 	// now render the main view
 	float fovratio;
-	float ratio = ratios[WidescreenRatio];
-	if (! Is54Aspect(WidescreenRatio))
+	float ratio = WidescreenRatio;
+	if (WidescreenRatio >= 1.3f)
 	{
 		fovratio = 1.333333f;
 	}
diff --git a/src/gl/scene/gl_sprite.cpp b/src/gl/scene/gl_sprite.cpp
index 07f397d6d..36e3e00ff 100644
--- a/src/gl/scene/gl_sprite.cpp
+++ b/src/gl/scene/gl_sprite.cpp
@@ -135,7 +135,6 @@ void GLSprite::CalculateVertices(FVector3 *v)
 
 	// [Nash] is a flat sprite
 	const bool isFlatSprite = (actor != nullptr) && (spritetype == RF_WALLSPRITE || spritetype == RF_FLATSPRITE);
-	const bool dontFlip = (actor != nullptr) && (actor->renderflags & RF_DONTFLIP);
 	const bool useOffsets = (actor != nullptr) && !(actor->renderflags & RF_ROLLCENTER);
 
 	// [Nash] check for special sprite drawing modes
@@ -176,37 +175,8 @@ void GLSprite::CalculateVertices(FVector3 *v)
 			yawvecY = actor->Angles.Yaw.Sin();
 		}
 
-		// [MC] This is the only thing that I changed in Nash's submission which 
-		// was constantly applying roll to everything. That was wrong. Flat sprites
-		// with roll literally look like paper thing space ships trying to swerve.
-		// However, it does well with wall sprites.
-		// Also, renamed FLOORSPRITE to FLATSPRITE because that's technically incorrect.
-		// I plan on adding proper FLOORSPRITEs which can actually curve along sloped
-		// 3D floors later... if possible.
-
-		// Here we need some form of priority in order to work.
-		if (spritetype == RF_FLATSPRITE)
-		{
-			float pitchDegrees = -actor->Angles.Pitch.Degrees;
-			DVector3 apos = { x, y, z };
-			DVector3 diff = ViewPos - apos;
-			DAngle angto = diff.Angle();
-
-			angto = deltaangle(actor->Angles.Yaw, angto);
-
-			bool noFlipSprite = (!dontFlip || (fabs(angto) < 90.));
-			mat.Rotate(0, 1, 0, (noFlipSprite) ? 0 : 180);
-
-			mat.Rotate(-yawvecY, 0, yawvecX, (noFlipSprite) ? -pitchDegrees : pitchDegrees);
-			if (drawRollSpriteActor)
-			{
-				if (useOffsets)	mat.Translate(xx, zz, yy);
-				mat.Rotate(yawvecX, 0, yawvecY, (noFlipSprite) ? -rollDegrees : rollDegrees);
-				if (useOffsets) mat.Translate(-xx, -zz, -yy);
-			}
-		}
 		// [fgsfds] Rotate the sprite about the sight vector (roll) 
-		else if (spritetype == RF_WALLSPRITE)
+		if (spritetype == RF_WALLSPRITE)
 		{
 			mat.Rotate(0, 1, 0, 0);
 			if (drawRollSpriteActor)
@@ -405,7 +375,13 @@ void GLSprite::Draw(int pass)
 			gl_RenderState.Apply();
 
 			FVector3 v[4];
-			CalculateVertices(v);
+			if ((actor->renderflags & RF_SPRITETYPEMASK) == RF_FLATSPRITE)
+			{
+			}
+			else
+			{
+				CalculateVertices(v);
+			}
 
 
 			FQuadDrawer qd;
@@ -461,7 +437,7 @@ inline void GLSprite::PutSprite(bool translucent)
 {
 	int list;
 	// [BB] Allow models to be drawn in the GLDL_TRANSLUCENT pass.
-	if (translucent || !modelframe)
+	if (translucent || (!modelframe && (actor->renderflags & RF_SPRITETYPEMASK) != RF_WALLSPRITE))
 	{
 		list = GLDL_TRANSLUCENT;
 	}
@@ -711,7 +687,7 @@ void GLSprite::Process(AActor* thing, sector_t * sector, int thruportal)
 	x = thingpos.X;
 	z = thingpos.Z;
 	y = thingpos.Y;
-	if (spritetype != RF_FLATSPRITE) z -= thing->Floorclip;
+	if (spritetype == RF_FACESPRITE) z -= thing->Floorclip; // wall and flat sprites are to be considered level geometry so this may not apply.
 
 	// [RH] Make floatbobbing a renderer-only effect.
 	if (thing->flags2 & MF2_FLOATBOB)
@@ -727,9 +703,19 @@ void GLSprite::Process(AActor* thing, sector_t * sector, int thruportal)
 		DAngle ang = (thingpos - ViewPos).Angle();
 		FTextureID patch;
 		if (thing->flags7 & MF7_SPRITEANGLE)
+		{
 			patch = gl_GetSpriteFrame(spritenum, thing->frame, -1, (thing->SpriteAngle).BAMs(), &mirror);
-		else
+		}
+		else if (!(thing->renderflags & RF_FLATSPRITE))
+		{
 			patch = gl_GetSpriteFrame(spritenum, thing->frame, -1, (ang - (thing->Angles.Yaw + thing->SpriteRotation)).BAMs(), &mirror);
+		}
+		else
+		{
+			// Flat sprites cannot rotate in a predictable manner.
+			patch = gl_GetSpriteFrame(spritenum, thing->frame, 0, 0, &mirror);
+		}
+
 		if (!patch.isValid()) return;
 		int type = thing->renderflags & RF_SPRITETYPEMASK;
 		gltexture = FMaterial::ValidateTexture(patch, (type == RF_FACESPRITE), false);
@@ -781,6 +767,9 @@ void GLSprite::Process(AActor* thing, sector_t * sector, int thruportal)
 			break;
 
 		case RF_FLATSPRITE:
+			// needs careful rethinking
+			return;
+
 		case RF_WALLSPRITE:
 			viewvecX = thing->Angles.Yaw.Cos();
 			viewvecY = thing->Angles.Yaw.Sin();
@@ -910,8 +899,7 @@ void GLSprite::Process(AActor* thing, sector_t * sector, int thruportal)
 		// This is a non-translucent sprite (i.e. STYLE_Normal or equivalent)
 		trans=1.f;
 		
-
-		if (!gl_sprite_blend || modelframe)
+		if (!gl_sprite_blend || modelframe || (thing->renderflags & RF_SPRITETYPEMASK) == RF_WALLSPRITE)
 		{
 			RenderStyle.SrcAlpha = STYLEALPHA_One;
 			RenderStyle.DestAlpha = STYLEALPHA_Zero;
diff --git a/src/gl/scene/gl_weapon.cpp b/src/gl/scene/gl_weapon.cpp
index 598254c10..db778679e 100644
--- a/src/gl/scene/gl_weapon.cpp
+++ b/src/gl/scene/gl_weapon.cpp
@@ -81,8 +81,6 @@ void FGLRenderer::DrawPSprite (player_t * player,DPSprite *psp, float sx, float
 	float			scale;
 	float			scalex;
 	float			ftexturemid;
-	                      // 4:3  16:9   16:10  17:10    5:4  17:10    21:9
-	static float xratio[] = {1.f, 3.f/4, 5.f/6, 40.f/51, 1.f, 40.f/51, 4.f/7};
 	
 	// [BB] In the HUD model step we just render the model and break out. 
 	if ( hudModelStep )
@@ -108,7 +106,7 @@ void FGLRenderer::DrawPSprite (player_t * player,DPSprite *psp, float sx, float
 	tex->GetSpriteRect(&r);
 
 	// calculate edges of the shape
-	scalex = xratio[WidescreenRatio] * vw / 320;
+	scalex = (320.0f / (240.0f * WidescreenRatio)) * vw / 320;
 
 	tx = sx - (160 - r.left);
 	x1 = tx * scalex + vw/2;
diff --git a/src/gl/stereo3d/gl_quadstereo.cpp b/src/gl/stereo3d/gl_quadstereo.cpp
index cd689d3b5..1388e6944 100644
--- a/src/gl/stereo3d/gl_quadstereo.cpp
+++ b/src/gl/stereo3d/gl_quadstereo.cpp
@@ -45,17 +45,38 @@ QuadStereo::QuadStereo(double ipdMeters)
 	// Check whether quad-buffered stereo is supported in the current context
 	// We are assuming the OpenGL context is already current at this point,
 	// i.e. this constructor is called "just in time".
-	GLboolean supportsStereo, supportsBuffered;
-	glGetBooleanv(GL_STEREO, &supportsStereo);
-	glGetBooleanv(GL_DOUBLEBUFFER, &supportsBuffered);
-	bQuadStereoSupported = supportsStereo && supportsBuffered;
-	leftEye.bQuadStereoSupported = bQuadStereoSupported;
-	rightEye.bQuadStereoSupported = bQuadStereoSupported;
 
-	eye_ptrs.Push(&leftEye);
-	// If stereo is not supported, just draw scene once (left eye view only)
-	if (bQuadStereoSupported) {
-		eye_ptrs.Push(&rightEye);
+	// First initialize to mono-ish initial state
+	bQuadStereoSupported = leftEye.bQuadStereoSupported = rightEye.bQuadStereoSupported = false;
+	eye_ptrs.Push(&leftEye); // We ALWAYS want to show at least this one view...
+	// We will possibly advance to true stereo mode in the Setup() method...
+}
+
+// Sometimes the stereo render context is not ready immediately at start up
+/* private */
+void QuadStereo::checkInitialRenderContextState()
+{
+	// Keep trying until we see at least one good OpenGL context to render to
+	static bool bDecentContextWasFound = false;
+	if (!bDecentContextWasFound) {
+		// I'm using a "random" OpenGL call (glGetFramebufferAttachmentParameteriv)
+		// that appears to correlate with whether the context is ready 
+		GLint attachmentType = GL_NONE;
+		glGetFramebufferAttachmentParameteriv(GL_DRAW_FRAMEBUFFER, GL_FRONT_LEFT, GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE, &attachmentType);
+		if (attachmentType != GL_NONE) // Finally, a useful OpenGL context
+		{
+			// This block will be executed exactly ONCE during a game run
+			bDecentContextWasFound = true; // now we can stop checking every frame...
+			// Now check whether this context supports hardware stereo
+			GLboolean supportsStereo, supportsBuffered;
+			glGetBooleanv(GL_STEREO, &supportsStereo);
+			glGetBooleanv(GL_DOUBLEBUFFER, &supportsBuffered);
+			bQuadStereoSupported = supportsStereo && supportsBuffered;
+			leftEye.bQuadStereoSupported = bQuadStereoSupported;
+			rightEye.bQuadStereoSupported = bQuadStereoSupported;
+			if (bQuadStereoSupported)
+				eye_ptrs.Push(&rightEye); // Use the other eye too, if we can do stereo
+		}
 	}
 }
 
@@ -81,11 +102,18 @@ void QuadStereo::Present() const
 	{
 		GLRenderer->mBuffers->BindOutputFB();
 		GLRenderer->ClearBorders();
-		GLRenderer->mBuffers->BindEyeTexture(1, 0);
+		GLRenderer->mBuffers->BindEyeTexture(0, 0);
 		GLRenderer->DrawPresentTexture(GLRenderer->mOutputLetterbox, true);
 	}
 }
 
+void QuadStereo::SetUp() const
+{
+	Stereo3DMode::SetUp();
+	// Maybe advance to true stereo mode (ONCE), after the stereo context is finally ready
+	const_cast<QuadStereo*>(this)->checkInitialRenderContextState();
+}
+
 /* static */
 const QuadStereo& QuadStereo::getInstance(float ipd)
 {
diff --git a/src/gl/stereo3d/gl_quadstereo.h b/src/gl/stereo3d/gl_quadstereo.h
index d9aa4f435..2c58c88c5 100644
--- a/src/gl/stereo3d/gl_quadstereo.h
+++ b/src/gl/stereo3d/gl_quadstereo.h
@@ -69,11 +69,13 @@ class QuadStereo : public Stereo3DMode
 public:
 	QuadStereo(double ipdMeters);
 	void Present() const override;
+	void SetUp() const override;
 	static const QuadStereo& getInstance(float ipd);
 private:
 	QuadStereoLeftPose leftEye;
 	QuadStereoRightPose rightEye;
 	bool bQuadStereoSupported;
+	void checkInitialRenderContextState();
 };
 
 
diff --git a/src/gl/system/gl_framebuffer.cpp b/src/gl/system/gl_framebuffer.cpp
index 158d7f333..ed0d07bd5 100644
--- a/src/gl/system/gl_framebuffer.cpp
+++ b/src/gl/system/gl_framebuffer.cpp
@@ -192,12 +192,23 @@ void OpenGLFrameBuffer::Update()
 	DrawRateStuff();
 	GLRenderer->Flush();
 
-	GLRenderer->SetOutputViewport(nullptr);
-
 	Swap();
 	swapped = false;
 	Unlock();
 	CheckBench();
+
+	if (Windowed)
+	{
+		int clientWidth = GetClientWidth();
+		int clientHeight = GetClientHeight();
+		if (clientWidth > 0 && clientHeight > 0 && (Width != clientWidth || Height != clientHeight))
+		{
+			Resize(clientWidth, clientHeight);
+			V_OutputResized(Width, Height);
+		}
+	}
+
+	GLRenderer->SetOutputViewport(nullptr);
 }
 
 
diff --git a/src/p_udmf.cpp b/src/p_udmf.cpp
index 0b054247e..c09debc51 100644
--- a/src/p_udmf.cpp
+++ b/src/p_udmf.cpp
@@ -309,6 +309,11 @@ void FUDMFKeys::Sort()
 
 FUDMFKey *FUDMFKeys::Find(FName key)
 {
+	if (!mSorted)
+	{
+		mSorted = true;
+		Sort();
+	}
 	int min = 0, max = Size()-1;
 
 	while (min <= max)
diff --git a/src/posix/cocoa/i_video.mm b/src/posix/cocoa/i_video.mm
index 624e8ad07..08a563b25 100644
--- a/src/posix/cocoa/i_video.mm
+++ b/src/posix/cocoa/i_video.mm
@@ -483,7 +483,7 @@ NSOpenGLPixelFormat* CreatePixelFormat(const OpenGLProfile profile)
 		attributes[i++] = NSOpenGLPFAAllowOfflineRenderers;
 	}
 
-	if (NSAppKitVersionNumber >= AppKit10_7 && OpenGLProfile::Core == profile)
+	if (NSAppKitVersionNumber >= AppKit10_7 && OpenGLProfile::Core == profile && 1 == vid_renderer)
 	{
 		NSOpenGLPixelFormatAttribute profile = NSOpenGLProfileVersion3_2Core;
 		const char* const glversion = Args->CheckValue("-glversion");
diff --git a/src/r_defs.h b/src/r_defs.h
index 862d1d2c4..f091b15b5 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -245,6 +245,7 @@ struct FUDMFKey
 
 class FUDMFKeys : public TArray<FUDMFKey>
 {
+	bool mSorted = false;
 public:
 	void Sort();
 	FUDMFKey *Find(FName key);
diff --git a/src/r_main.cpp b/src/r_main.cpp
index ce4841a2e..d84698b7c 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -232,7 +232,7 @@ void R_SetVisibility(double vis)
 	else
 		r_WallVisibility = r_BaseVisibility;
 
-	r_WallVisibility = (InvZtoScale * SCREENWIDTH*BaseRatioSizes[WidescreenRatio][1] /
+	r_WallVisibility = (InvZtoScale * SCREENWIDTH*AspectBaseHeight(WidescreenRatio) /
 		(viewwidth*SCREENHEIGHT*3)) * (r_WallVisibility * FocalTangent);
 
 	// Prevent overflow on floors/ceilings. Note that the calculation of
@@ -295,7 +295,7 @@ CCMD (r_visibility)
 //
 //==========================================================================
 
-void R_SWRSetWindow(int windowSize, int fullWidth, int fullHeight, int stHeight, int trueratio)
+void R_SWRSetWindow(int windowSize, int fullWidth, int fullHeight, int stHeight, float trueratio)
 {
 	int virtheight, virtwidth, virtwidth2, virtheight2;
 
@@ -318,22 +318,22 @@ void R_SWRSetWindow(int windowSize, int fullWidth, int fullHeight, int stHeight,
 	virtwidth = virtwidth2 = fullWidth;
 	virtheight = virtheight2 = fullHeight;
 
-	if (Is54Aspect(trueratio))
+	if (trueratio < 1.3f)
 	{
-		virtheight2 = virtheight2 * BaseRatioSizes[trueratio][3] / 48;
+		virtheight2 = virtheight2 * AspectMultiplier(trueratio) / 48;
 	}
 	else
 	{
-		virtwidth2 = virtwidth2 * BaseRatioSizes[trueratio][3] / 48;
+		virtwidth2 = virtwidth2 * AspectMultiplier(trueratio) / 48;
 	}
 
-	if (Is54Aspect(WidescreenRatio))
+	if (WidescreenRatio < 1.3f)
 	{
-		virtheight = virtheight * BaseRatioSizes[WidescreenRatio][3] / 48;
+		virtheight = virtheight * AspectMultiplier(WidescreenRatio) / 48;
 	}
 	else
 	{
-		virtwidth = virtwidth * BaseRatioSizes[WidescreenRatio][3] / 48;
+		virtwidth = virtwidth * AspectMultiplier(WidescreenRatio) / 48;
 	}
 
 	BaseYaspectMul = 320.0 * virtheight2 / (r_Yaspect * virtwidth2);
@@ -678,7 +678,7 @@ void R_EnterPortal (PortalDrawseg* pds, int depth)
 			ViewPos.X = (x1 + r * dx)*2 - x;
 			ViewPos.Y = (y1 + r * dy)*2 - y;
 		}
-		ViewAngle = pds->src->Delta().Angle() - startang;
+		ViewAngle = pds->src->Delta().Angle() * 2 - startang;
 	}
 	else
 	{
diff --git a/src/r_renderer.h b/src/r_renderer.h
index 6c65fc12f..a39520b49 100644
--- a/src/r_renderer.h
+++ b/src/r_renderer.h
@@ -55,7 +55,7 @@ struct FRenderer
 	virtual void ErrorCleanup () {}
 	virtual void ClearBuffer(int color) = 0;
 	virtual void Init() = 0;
-	virtual void SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight, int trueratio) {}
+	virtual void SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight, float trueratio) {}
 	virtual void SetupFrame(player_t *player) {}
 	virtual void CopyStackedViewParameters() {}
 	virtual void RenderTextureView (FCanvasTexture *tex, AActor *viewpoint, int fov) = 0;
diff --git a/src/r_swrenderer.cpp b/src/r_swrenderer.cpp
index 07edf25e9..4d1fd0371 100644
--- a/src/r_swrenderer.cpp
+++ b/src/r_swrenderer.cpp
@@ -45,7 +45,7 @@
 
 
 class FArchive;
-void R_SWRSetWindow(int windowSize, int fullWidth, int fullHeight, int stHeight, int trueratio);
+void R_SWRSetWindow(int windowSize, int fullWidth, int fullHeight, int stHeight, float trueratio);
 void R_SetupColormap(player_t *);
 void R_SetupFreelook();
 void R_InitRenderer();
@@ -275,7 +275,7 @@ void FSoftwareRenderer::ClearBuffer(int color)
 //
 //===========================================================================
 
-void FSoftwareRenderer::SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight, int trueratio)
+void FSoftwareRenderer::SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight, float trueratio)
 {
 	R_SWRSetWindow(windowSize, fullWidth, fullHeight, stHeight, trueratio);
 }
diff --git a/src/r_swrenderer.h b/src/r_swrenderer.h
index 3e5fed9bc..2856d9586 100644
--- a/src/r_swrenderer.h
+++ b/src/r_swrenderer.h
@@ -30,7 +30,7 @@ struct FSoftwareRenderer : public FRenderer
 	void ErrorCleanup ();
 	void ClearBuffer(int color);
 	void Init();
-	void SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight, int trueratio);
+	void SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight, float trueratio);
 	void SetupFrame(player_t *player);
 	void CopyStackedViewParameters();
 	void RenderTextureView (FCanvasTexture *tex, AActor *viewpoint, int fov);
diff --git a/src/r_things.cpp b/src/r_things.cpp
index 28b52129b..a62525d08 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -1393,7 +1393,7 @@ void R_DrawPSprite(DPSprite *pspr, AActor *owner, float bobx, float boby, double
 	}
 	if (pspr->GetID() < PSP_TARGETCENTER)
 	{ // Move the weapon down for 1280x1024.
-		vis->texturemid -= BaseRatioSizes[WidescreenRatio][2];
+		vis->texturemid -= AspectPspriteOffset(WidescreenRatio);
 	}
 	vis->x1 = x1 < 0 ? 0 : x1;
 	vis->x2 = x2 >= viewwidth ? viewwidth : x2;
diff --git a/src/r_utility.cpp b/src/r_utility.cpp
index 00ac91c97..8e4284b7e 100644
--- a/src/r_utility.cpp
+++ b/src/r_utility.cpp
@@ -138,7 +138,7 @@ angle_t			LocalViewAngle;
 int				LocalViewPitch;
 bool			LocalKeyboardTurner;
 
-int				WidescreenRatio;
+float			WidescreenRatio;
 int				setblocks;
 int				extralight;
 bool			setsizeneeded;
@@ -200,7 +200,7 @@ void R_SetViewSize (int blocks)
 
 void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 {
-	int trueratio;
+	float trueratio;
 
 	if (windowSize >= 11)
 	{
@@ -220,8 +220,7 @@ void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 		freelookviewheight = ((setblocks*fullHeight)/10)&~7;
 	}
 
-	// If the screen is approximately 16:9 or 16:10, consider it widescreen.
-	WidescreenRatio = CheckRatio (fullWidth, fullHeight, &trueratio);
+	WidescreenRatio = ActiveRatio (fullWidth, fullHeight, &trueratio);
 
 	DrawFSHUD = (windowSize == 11);
 	
@@ -230,13 +229,13 @@ void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 
 	centery = viewheight/2;
 	centerx = viewwidth/2;
-	if (Is54Aspect(WidescreenRatio))
+	if (WidescreenRatio < 1.3f)
 	{
 		centerxwide = centerx;
 	}
 	else
 	{
-		centerxwide = centerx * BaseRatioSizes[WidescreenRatio][3] / 48;
+		centerxwide = centerx * AspectMultiplier(WidescreenRatio) / 48;
 	}
 
 
diff --git a/src/r_utility.h b/src/r_utility.h
index 8cabfa600..e9fd436e5 100644
--- a/src/r_utility.h
+++ b/src/r_utility.h
@@ -33,7 +33,7 @@ extern int				validcount;
 extern angle_t			LocalViewAngle;			// [RH] Added to consoleplayer's angle
 extern int				LocalViewPitch;			// [RH] Used directly instead of consoleplayer's pitch
 extern bool				LocalKeyboardTurner;	// [RH] The local player used the keyboard to turn, so interpolate
-extern int				WidescreenRatio;
+extern float			WidescreenRatio;
 
 extern double			r_TicFracF;
 extern DWORD			r_FrameTime;
diff --git a/src/sound/fmodsound.cpp b/src/sound/fmodsound.cpp
index 2db5a98a1..c130b7e6a 100644
--- a/src/sound/fmodsound.cpp
+++ b/src/sound/fmodsound.cpp
@@ -971,6 +971,7 @@ bool FMODSoundRenderer::Init()
 
 #if FMOD_STUDIO
 	FMOD_ADVANCEDSETTINGS advSettings = {};
+	advSettings.cbSize = sizeof advSettings;
 	advSettings.resamplerMethod = resampler;
 	result = Sys->setAdvancedSettings(&advSettings);
 	if (result != FMOD_OK)
@@ -1370,11 +1371,8 @@ void FMODSoundRenderer::PrintStatus()
 {
 	FMOD_OUTPUTTYPE output;
 	FMOD_SPEAKERMODE speakermode;
-	FMOD_SOUND_FORMAT format;
-	FMOD_DSP_RESAMPLER resampler;
 	int driver;
 	int samplerate;
-	int numoutputchannels;
 	unsigned int bufferlength;
 	int numbuffers;
 
@@ -1413,6 +1411,9 @@ void FMODSoundRenderer::PrintStatus()
 #endif
 	}
 #if !FMOD_STUDIO
+	FMOD_SOUND_FORMAT format;
+	FMOD_DSP_RESAMPLER resampler;
+	int numoutputchannels;
 	if (FMOD_OK == Sys->getSoftwareFormat(&samplerate, &format, &numoutputchannels, NULL, &resampler, NULL))
 	{
 		Printf (TEXTCOLOR_LIGHTBLUE "Software mixer sample rate: " TEXTCOLOR_GREEN "%d\n", samplerate);
@@ -2758,6 +2759,16 @@ std::pair<SoundHandle,bool> FMODSoundRenderer::LoadSoundRaw(BYTE *sfxdata, int l
 	exinfo.defaultfrequency = frequency;
 	switch (bits)
 	{
+#if FMOD_STUDIO
+	case -8:
+		// Need to convert sample data from signed to unsigned.
+		for (int i = 0; i < length; i++)
+		{
+			sfxdata[i] ^= 0x80;
+		}
+
+	case 8:
+#else // !FMOD_STUDIO
 	case 8:
 		// Need to convert sample data from unsigned to signed.
 		for (int i = 0; i < length; ++i)
@@ -2766,6 +2777,7 @@ std::pair<SoundHandle,bool> FMODSoundRenderer::LoadSoundRaw(BYTE *sfxdata, int l
 		}
 
 	case -8:
+#endif // FMOD_STUDIO
 		exinfo.format = FMOD_SOUND_FORMAT_PCM8;
 		numsamples = length;
 		break;
diff --git a/src/v_draw.cpp b/src/v_draw.cpp
index dada0cd57..a33fd618b 100644
--- a/src/v_draw.cpp
+++ b/src/v_draw.cpp
@@ -863,37 +863,37 @@ bool DCanvas::ParseDrawTextureTags (FTexture *img, double x, double y, DWORD tag
 void DCanvas::VirtualToRealCoords(double &x, double &y, double &w, double &h,
 	double vwidth, double vheight, bool vbottom, bool handleaspect) const
 {
-	int myratio = handleaspect ? CheckRatio (Width, Height) : 0;
+	float myratio = handleaspect ? ActiveRatio (Width, Height) : (4.0f / 3.0f);
 
     // if 21:9 AR, map to 16:9 for all callers.
     // this allows for black bars and stops the stretching of fullscreen images
-    if (myratio == 6) {
-        myratio = 2;
+    if (myratio > 1.7f) {
+        myratio = 16.0f / 9.0f;
     }
 
 	double right = x + w;
 	double bottom = y + h;
 
-	if (myratio != 0 && myratio != 4)
+	if (myratio > 1.4f)
 	{ // The target surface is either 16:9 or 16:10, so expand the
 	  // specified virtual size to avoid undesired stretching of the
 	  // image. Does not handle non-4:3 virtual sizes. I'll worry about
 	  // those if somebody expresses a desire to use them.
-		x = (x - vwidth * 0.5) * Width * 960 / (vwidth * BaseRatioSizes[myratio][0]) + Width * 0.5;
-		w = (right - vwidth * 0.5) * Width * 960 / (vwidth * BaseRatioSizes[myratio][0]) + Width * 0.5 - x;
+		x = (x - vwidth * 0.5) * Width * 960 / (vwidth * AspectBaseWidth(myratio)) + Width * 0.5;
+		w = (right - vwidth * 0.5) * Width * 960 / (vwidth * AspectBaseWidth(myratio)) + Width * 0.5 - x;
 	}
 	else
 	{
 		x = x * Width / vwidth;
 		w = right * Width / vwidth - x;
 	}
-	if (myratio == 4)
+	if (myratio < 1.3f)
 	{ // The target surface is 5:4
-		y = (y - vheight * 0.5) * Height * 600 / (vheight * BaseRatioSizes[myratio][1]) + Height * 0.5;
-		h = (bottom - vheight * 0.5) * Height * 600 / (vheight * BaseRatioSizes[myratio][1]) + Height * 0.5 - y;
+		y = (y - vheight * 0.5) * Height * 600 / (vheight * AspectBaseHeight(myratio)) + Height * 0.5;
+		h = (bottom - vheight * 0.5) * Height * 600 / (vheight * AspectBaseHeight(myratio)) + Height * 0.5 - y;
 		if (vbottom)
 		{
-			y += (Height - Height * BaseRatioSizes[myratio][3] / 48.0) * 0.5;
+			y += (Height - Height * AspectMultiplier(myratio) / 48.0) * 0.5;
 		}
 	}
 	else
@@ -937,30 +937,30 @@ void DCanvas::VirtualToRealCoordsInt(int &x, int &y, int &w, int &h,
 
 void DCanvas::FillBorder (FTexture *img)
 {
-	int myratio = CheckRatio (Width, Height);
+	float myratio = ActiveRatio (Width, Height);
 
     // if 21:9 AR, fill borders akin to 16:9, since all fullscreen
     // images are being drawn to that scale.
-    if (myratio == 6) {
-        myratio = 2;
+    if (myratio > 1.7f) {
+        myratio = 16 / 9.0f;
     }
 
-	if (myratio == 0)
+	if (myratio >= 1.3f && myratio <= 1.4f)
 	{ // This is a 4:3 display, so no border to show
 		return;
 	}
 	int bordtop, bordbottom, bordleft, bordright, bord;
-	if (Is54Aspect(myratio))
+	if (myratio < 1.3f)
 	{ // Screen is taller than it is wide
 		bordleft = bordright = 0;
-		bord = Height - Height * BaseRatioSizes[myratio][3] / 48;
+		bord = Height - Height * AspectMultiplier(myratio) / 48;
 		bordtop = bord / 2;
 		bordbottom = bord - bordtop;
 	}
 	else
 	{ // Screen is wider than it is tall
 		bordtop = bordbottom = 0;
-		bord = Width - Width * BaseRatioSizes[myratio][3] / 48;
+		bord = Width - Width * AspectMultiplier(myratio) / 48;
 		bordleft = bord / 2;
 		bordright = bord - bordleft;
 	}
diff --git a/src/v_video.cpp b/src/v_video.cpp
index b9917a1cb..20e1f526c 100644
--- a/src/v_video.cpp
+++ b/src/v_video.cpp
@@ -725,6 +725,21 @@ void DCanvas::CalcGamma (float gamma, BYTE gammalookup[256])
 DSimpleCanvas::DSimpleCanvas (int width, int height)
 	: DCanvas (width, height)
 {
+	MemBuffer = nullptr;
+	Resize(width, height);
+}
+
+void DSimpleCanvas::Resize(int width, int height)
+{
+	Width = width;
+	Height = height;
+
+	if (MemBuffer != NULL)
+	{
+		delete[] MemBuffer;
+		MemBuffer = NULL;
+	}
+
 	// Making the pitch a power of 2 is very bad for performance
 	// Try to maximize the number of cache lines that can be filled
 	// for each column drawing operation by making the pitch slightly
@@ -761,7 +776,7 @@ DSimpleCanvas::DSimpleCanvas (int width, int height)
 		}
 	}
 	MemBuffer = new BYTE[Pitch * height];
-	memset (MemBuffer, 0, Pitch * height);
+	memset(MemBuffer, 0, Pitch * height);
 }
 
 //==========================================================================
@@ -1259,7 +1274,6 @@ CCMD(clean)
 bool V_DoModeSetup (int width, int height, int bits)
 {
 	DFrameBuffer *buff = I_SetMode (width, height, screen);
-	int cx1, cx2;
 
 	if (buff == NULL)
 	{
@@ -1274,6 +1288,17 @@ bool V_DoModeSetup (int width, int height, int bits)
 	// if D3DFB is being used for the display.
 	FFont::StaticPreloadFonts();
 
+	DisplayBits = bits;
+	V_UpdateModeSize(width, height);
+
+	M_RefreshModesList ();
+
+	return true;
+}
+
+void V_UpdateModeSize (int width, int height)
+{
+	int cx1, cx2;
 	V_CalcCleanFacs(320, 200, width, height, &CleanXfac, &CleanYfac, &cx1, &cx2);
 
 	CleanWidth = width / CleanXfac;
@@ -1314,32 +1339,37 @@ bool V_DoModeSetup (int width, int height, int bits)
 
 	DisplayWidth = width;
 	DisplayHeight = height;
-	DisplayBits = bits;
 
 	R_OldBlend = ~0;
 	Renderer->OnModeSet();
-	
-	M_RefreshModesList ();
+}
 
-	return true;
+void V_OutputResized (int width, int height)
+{
+	V_UpdateModeSize(width, height);
+	setsizeneeded = true;
+	if (StatusBar != NULL)
+	{
+		StatusBar->ScreenSizeChanged();
+	}
 }
 
 void V_CalcCleanFacs (int designwidth, int designheight, int realwidth, int realheight, int *cleanx, int *cleany, int *_cx1, int *_cx2)
 {
-	int ratio;
+	float ratio;
 	int cwidth;
 	int cheight;
 	int cx1, cy1, cx2, cy2;
 
-	ratio = CheckRatio(realwidth, realheight);
-	if (Is54Aspect(ratio))
+	ratio = ActiveRatio(realwidth, realheight);
+	if (ratio < 1.3f)
 	{
 		cwidth = realwidth;
-		cheight = realheight * BaseRatioSizes[ratio][3] / 48;
+		cheight = realheight * AspectMultiplier(ratio) / 48;
 	}
 	else
 	{
-		cwidth = realwidth * BaseRatioSizes[ratio][3] / 48;
+		cwidth = realwidth * AspectMultiplier(ratio) / 48;
 		cheight = realheight;
 	}
 	// Use whichever pair of cwidth/cheight or width/height that produces less difference
@@ -1573,20 +1603,10 @@ CUSTOM_CVAR (Int, vid_aspect, 0, CVAR_GLOBALCONFIG|CVAR_ARCHIVE)
 	}
 }
 
-// Tries to guess the physical dimensions of the screen based on the
-// screen's pixel dimensions. Can return:
-// 0: 4:3
-// 1: 16:9
-// 2: 16:10
-// 3: 17:10
-// 4: 5:4
-// 5: 17:10 (redundant)
-// 6: 21:9
-int CheckRatio (int width, int height, int *trueratio)
+// Helper for ActiveRatio and CheckRatio. Returns the forced ratio type, or -1 if none.
+int ActiveFakeRatio(int width, int height)
 {
 	int fakeratio = -1;
-	int ratio;
-
 	if ((vid_aspect >= 1) && (vid_aspect <= 6))
 	{
 		// [SP] User wants to force aspect ratio; let them.
@@ -1598,7 +1618,7 @@ int CheckRatio (int width, int height, int *trueratio)
 		else if (fakeratio == 5)
 		{
 			fakeratio = 3;
-		}        
+		}
 	}
 	if (vid_nowidescreen)
 	{
@@ -1608,74 +1628,98 @@ int CheckRatio (int width, int height, int *trueratio)
 		}
 		else
 		{
-			fakeratio = (height * 5/4 == width) ? 4 : 0;
+			fakeratio = (height * 5 / 4 == width) ? 4 : 0;
 		}
 	}
-	// If the size is approximately 16:9, consider it so.
-	if (abs (height * 16/9 - width) < 10)
-	{
-		ratio = 1;
-	}
-	// Consider 17:10 as well.
-	else if (abs (height * 17/10 - width) < 10)
-	{
-		ratio = 3;
-	}
-	// 16:10 has more variance in the pixel dimensions. Grr.
-	else if (abs (height * 16/10 - width) < 60)
-	{
-		// 320x200 and 640x400 are always 4:3, not 16:10
-		if ((width == 320 && height == 200) || (width == 640 && height == 400))
-		{
-			ratio = 0;
-		}
-		else
-		{
-			ratio = 2;
-		}
-	}
-	// Unless vid_tft is set, 1280x1024 is 4:3, not 5:4.
-	else if (height * 5/4 == width && vid_tft)
-	{
-		ratio = 4;
-	}
-    // test for 21:9 (actually 64:27, 21:9 is a semi-accurate ratio used in marketing)
-    else if (abs (height * 64/27 - width) < 30)
-    {
-        ratio = 6;
-    }
-	// Assume anything else is 4:3. (Which is probably wrong these days...)
-	else
-	{
-		ratio = 0;
-	}
-
-	if (trueratio != NULL)
-	{
-		*trueratio = ratio;
-	}
-	return (fakeratio >= 0) ? fakeratio : ratio;
+	return fakeratio;
 }
 
-// First column: Base width
-// Second column: Base height (used for wall visibility multiplier)
-// Third column: Psprite offset (needed for "tallscreen" modes)
-// Fourth column: Width or height multiplier
-
-// For widescreen aspect ratio x:y ...
-//     base_width = 240 * x / y
-//     multiplier = 320 / base_width
-//     base_height = 200 * multiplier
-const int BaseRatioSizes[7][4] =
+// Active screen ratio based on cvars and size
+float ActiveRatio(int width, int height, float *trueratio)
 {
-	{  960, 600, 0,                   48 },			//  4:3   320,      200,      multiplied by three
-	{ 1280, 450, 0,                   48*3/4 },		// 16:9   426.6667, 150,      multiplied by three
-	{ 1152, 500, 0,                   48*5/6 },		// 16:10  386,      166.6667, multiplied by three
-	{ 1224, 471, 0,                   48*40/51 },	// 17:10  408,		156.8627, multiplied by three
-	{  960, 640, (int)(6.5*FRACUNIT), 48*15/16 },   //  5:4   320,      213.3333, multiplied by three
-	{ 1224, 471, 0,                   48*40/51 },	// 17:10  408,		156.8627, multiplied by three (REDUNDANT)
-	{ 1707, 338, 0,                   48*9/16 }     	// 21:9   568.8889, 337.5,    multiplied by three
-};
+	static float forcedRatioTypes[] =
+	{
+		4 / 3.0f,
+		16 / 9.0f,
+		16 / 10.0f,
+		17 / 10.0f,
+		5 / 4.0f,
+		17 / 10.0f,
+		21 / 9.0f
+	};
+
+	float ratio = width / (float)height;
+	int fakeratio = ActiveFakeRatio(width, height);
+
+	if (trueratio)
+		*trueratio = ratio;
+	return (fakeratio != -1) ? forcedRatioTypes[fakeratio] : ratio;
+}
+
+// Tries to guess the physical dimensions of the screen based on the
+// screen's pixel dimensions. Can return:
+// 0: 4:3
+// 1: 16:9
+// 2: 16:10
+// 3: 17:10
+// 4: 5:4
+// 5: 17:10 (redundant, never returned)
+// 6: 21:9
+int CheckRatio (int width, int height, int *trueratio)
+{
+	float aspect = width / (float)height;
+
+	static std::pair<float, int> ratioTypes[] =
+	{
+		{ 21 / 9.0f , 6 },
+		{ 16 / 9.0f , 1 },
+		{ 17 / 10.0f , 3 },
+		{ 16 / 10.0f , 2 },
+		{ 4 / 3.0f , 0 },
+		{ 5 / 4.0f , 4 },
+		{ 0.0f, 0 }
+	};
+
+	int ratio = ratioTypes[0].second;
+	float distance = fabs(ratioTypes[0].first - aspect);
+	for (int i = 1; ratioTypes[i].first != 0.0f; i++)
+	{
+		float d = fabs(ratioTypes[i].first - aspect);
+		if (d < distance)
+		{
+			ratio = ratioTypes[i].second;
+			distance = d;
+		}
+	}
+
+	int fakeratio = ActiveFakeRatio(width, height);
+	if (fakeratio == -1)
+		fakeratio = ratio;
+
+	if (trueratio)
+		*trueratio = ratio;
+	return fakeratio;
+}
+
+int AspectBaseWidth(float aspect)
+{
+	return (int)round(240.0f * aspect * 3.0f);
+}
+
+int AspectBaseHeight(float aspect)
+{
+	return (int)round(200.0f * (320.0f / (240.0f * aspect)) * 3.0f);
+}
+
+int AspectPspriteOffset(float aspect)
+{
+	return aspect < 1.3f ? (int)(6.5*FRACUNIT) : 0;
+}
+
+int AspectMultiplier(float aspect)
+{
+	return (int)round(320.0f / (240.0f * aspect) * 48.0f);
+}
 
 void IVideo::DumpAdapters ()
 {
diff --git a/src/v_video.h b/src/v_video.h
index 4f0a78675..8d785e43f 100644
--- a/src/v_video.h
+++ b/src/v_video.h
@@ -47,6 +47,8 @@ extern int CleanWidth_1, CleanHeight_1, CleanXfac_1, CleanYfac_1;
 extern int DisplayWidth, DisplayHeight, DisplayBits;
 
 bool V_DoModeSetup (int width, int height, int bits);
+void V_UpdateModeSize (int width, int height);
+void V_OutputResized (int width, int height);
 void V_CalcCleanFacs (int designwidth, int designheight, int realwidth, int realheight, int *cleanx, int *cleany, int *cx1=NULL, int *cx2=NULL);
 
 class FTexture;
@@ -300,6 +302,8 @@ public:
 	void Unlock ();
 
 protected:
+	void Resize(int width, int height);
+
 	BYTE *MemBuffer;
 
 	DSimpleCanvas() {}
@@ -512,15 +516,15 @@ extern "C" void ASM_PatchPitch (void);
 
 int CheckRatio (int width, int height, int *trueratio=NULL);
 static inline int CheckRatio (double width, double height) { return CheckRatio(int(width), int(height)); }
-extern const int BaseRatioSizes[7][4];
+inline bool IsRatioWidescreen(int ratio) { return (ratio & 3) != 0; }
 
-inline bool IsRatioWidescreen(int ratio) {
-    return (ratio & 3)!=0;
-}
+float ActiveRatio (int width, int height, float *trueratio = NULL);
+static inline double ActiveRatio (double width, double height) { return ActiveRatio(int(width), int(height)); }
 
-inline bool Is54Aspect(int ratio) {
-    return ratio == 4;
-}
+int AspectBaseWidth(float aspect);
+int AspectBaseHeight(float aspect);
+int AspectPspriteOffset(float aspect);
+int AspectMultiplier(float aspect);
 
 EXTERN_CVAR(Int, uiscale);
 
diff --git a/src/win32/fb_d3d9.cpp b/src/win32/fb_d3d9.cpp
index efdced151..06bfa0569 100644
--- a/src/win32/fb_d3d9.cpp
+++ b/src/win32/fb_d3d9.cpp
@@ -1220,6 +1220,24 @@ void D3DFB::Flip()
 		CurrRenderTexture ^= RenderTextureToggle;
 		TempRenderTexture = RenderTexture[CurrRenderTexture];
 	}
+
+	if (Windowed)
+	{
+		RECT box;
+		GetClientRect(Window, &box);
+		if (box.right > 0 && box.right > 0 && (Width != box.right || Height != box.bottom))
+		{
+			Resize(box.right, box.bottom);
+
+			TrueHeight = Height;
+			PixelDoubling = 0;
+			LBOffsetI = 0;
+			LBOffset = 0.0f;
+			Reset();
+
+			V_OutputResized(Width, Height);
+		}
+	}
 }
 
 //==========================================================================
diff --git a/src/win32/i_input.cpp b/src/win32/i_input.cpp
index 2b0659c83..1e6390392 100644
--- a/src/win32/i_input.cpp
+++ b/src/win32/i_input.cpp
@@ -537,10 +537,18 @@ LRESULT CALLBACK WndProc (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 		if (screen && !VidResizing)
 		{
 			LPMINMAXINFO mmi = (LPMINMAXINFO)lParam;
-			RECT rect = { 0, 0, screen->GetWidth(), screen->GetHeight() };
-			AdjustWindowRectEx(&rect, WS_VISIBLE|WS_OVERLAPPEDWINDOW, FALSE, WS_EX_APPWINDOW);
-			mmi->ptMinTrackSize.x = rect.right - rect.left;
-			mmi->ptMinTrackSize.y = rect.bottom - rect.top;
+			if (screen->IsFullscreen())
+			{
+				RECT rect = { 0, 0, screen->GetWidth(), screen->GetHeight() };
+				AdjustWindowRectEx(&rect, WS_VISIBLE | WS_OVERLAPPEDWINDOW, FALSE, WS_EX_APPWINDOW);
+				mmi->ptMinTrackSize.x = rect.right - rect.left;
+				mmi->ptMinTrackSize.y = rect.bottom - rect.top;
+			}
+			else
+			{
+				mmi->ptMinTrackSize.x = 320;
+				mmi->ptMinTrackSize.y = 200;
+			}
 			return 0;
 		}
 		break;