diff --git a/CMakeLists.txt b/CMakeLists.txt
index 85349d888..813560be1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -167,6 +167,11 @@ else()
 	set( ALL_C_FLAGS "" )
 	set( REL_C_FLAGS "" )
 	set( DEB_C_FLAGS "" )
+
+	# If we're compiling with a custom GCC on the Mac (which we know since g++-4.2 doesn't support C++11) statically link libgcc.
+	if( APPLE AND "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" )
+		set( ALL_C_FLAGS "-static-libgcc" )
+	endif()
 endif()
 
 set( CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} ${REL_LINKER_FLAGS}" )
@@ -193,7 +198,7 @@ option(FORCE_INTERNAL_GME "Use internal gme" ON)
 # Fast math flags, required by some subprojects
 set( ZD_FASTMATH_FLAG "" )
 if( ZD_CMAKE_COMPILER_IS_GNUCXX_COMPATIBLE )
-	set( ZD_FASTMATH_FLAG "-ffast-math" )
+	set( ZD_FASTMATH_FLAG "-ffast-math -ffp-contract=fast" )
 elseif( MSVC )
 	set( ZD_FASTMATH_FLAG "/fp:fast" )
 endif()
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 4c0834da3..3c80613ec 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -494,28 +494,28 @@ if( ZD_CMAKE_COMPILER_IS_GNUCXX_COMPATIBLE )
 		set( CMAKE_C_FLAGS "-Wno-unused-result ${CMAKE_C_FLAGS}" )
 		set( CMAKE_CXX_FLAGS "-Wno-unused-result ${CMAKE_CXX_FLAGS}" )
 	endif()
-	set( CMAKE_C_FLAGS "-Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-missing-field-initializers ${CMAKE_C_FLAGS}" )
-	set( CMAKE_CXX_FLAGS "-Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-missing-field-initializers ${CMAKE_CXX_FLAGS}" )
+	set( CMAKE_C_FLAGS "-Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-missing-field-initializers -ffp-contract=off ${CMAKE_C_FLAGS}" )
+	set( CMAKE_CXX_FLAGS "-Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-missing-field-initializers -ffp-contract=off ${CMAKE_CXX_FLAGS}" )
 
 	# Use the highest C++ standard available since VS2015 compiles with C++14
 	# but we only require C++11.  The recommended way to do this in CMake is to
 	# probably to use target_compile_features, but I don't feel like maintaining
 	# a list of features we use.
-	CHECK_CXX_COMPILER_FLAG( "-std=c++14" CAN_DO_CPP14 )
+	CHECK_CXX_COMPILER_FLAG( "-std=gnu++14" CAN_DO_CPP14 )
 	if ( CAN_DO_CPP14 )
-		set ( CMAKE_CXX_FLAGS "-std=c++14 ${CMAKE_CXX_FLAGS}" )
+		set ( CMAKE_CXX_FLAGS "-std=gnu++14 ${CMAKE_CXX_FLAGS}" )
 	else ()
-		CHECK_CXX_COMPILER_FLAG( "-std=c++1y" CAN_DO_CPP1Y )
+		CHECK_CXX_COMPILER_FLAG( "-std=gnu++1y" CAN_DO_CPP1Y )
 		if ( CAN_DO_CPP1Y )
-			set ( CMAKE_CXX_FLAGS "-std=c++1y ${CMAKE_CXX_FLAGS}" )
+			set ( CMAKE_CXX_FLAGS "-std=gnu++1y ${CMAKE_CXX_FLAGS}" )
 		else ()
-			CHECK_CXX_COMPILER_FLAG( "-std=c++11" CAN_DO_CPP11 )
+			CHECK_CXX_COMPILER_FLAG( "-std=gnu++11" CAN_DO_CPP11 )
 			if ( CAN_DO_CPP11 )
-				set ( CMAKE_CXX_FLAGS "-std=c++11 ${CMAKE_CXX_FLAGS}" )
+				set ( CMAKE_CXX_FLAGS "-std=gnu++11 ${CMAKE_CXX_FLAGS}" )
 			else ()
-				CHECK_CXX_COMPILER_FLAG( "-std=c++0x" CAN_DO_CPP0X )
+				CHECK_CXX_COMPILER_FLAG( "-std=gnu++0x" CAN_DO_CPP0X )
 				if ( CAN_DO_CPP0X )
-					set ( CMAKE_CXX_FLAGS "-std=c++0x ${CMAKE_CXX_FLAGS}" )
+					set ( CMAKE_CXX_FLAGS "-std=gnu++0x ${CMAKE_CXX_FLAGS}" )
 				endif ()
 			endif ()
 		endif ()
@@ -676,6 +676,7 @@ set( PLAT_COCOA_SOURCES
 	posix/cocoa/i_input.mm
 	posix/cocoa/i_joystick.cpp
 	posix/cocoa/i_main.mm
+	posix/cocoa/i_main_except.cpp
 	posix/cocoa/i_system.mm
 	posix/cocoa/i_timer.cpp
 	posix/cocoa/i_video.mm
@@ -712,6 +713,7 @@ elseif( APPLE )
 
 	set_source_files_properties( posix/osx/zdoom.icns PROPERTIES MACOSX_PACKAGE_LOCATION Resources )
 	set_source_files_properties( "${FMOD_LIBRARY}" PROPERTIES MACOSX_PACKAGE_LOCATION Frameworks )
+	set_source_files_properties( posix/osx/iwadpicker_cocoa.mm PROPERTIES COMPILE_FLAGS -fobjc-exceptions )
 else()
 	set( SYSTEM_SOURCES_DIR posix posix/sdl )
 	set( SYSTEM_SOURCES ${PLAT_POSIX_SOURCES} ${PLAT_SDL_SOURCES} )
diff --git a/src/am_map.cpp b/src/am_map.cpp
index 6fde814bf..8fab7e5ac 100644
--- a/src/am_map.cpp
+++ b/src/am_map.cpp
@@ -121,6 +121,7 @@ CVAR (Color, am_thingcolor_monster,	0xfcfcfc,	CVAR_ARCHIVE);
 CVAR (Color, am_thingcolor_ncmonster,	0xfcfcfc,	CVAR_ARCHIVE);
 CVAR (Color, am_thingcolor_item,	0xfcfcfc,	CVAR_ARCHIVE);
 CVAR (Color, am_thingcolor_citem,	0xfcfcfc,	CVAR_ARCHIVE);
+CVAR (Color, am_portalcolor,		0x404040,	CVAR_ARCHIVE);
 
 CVAR (Color, am_ovyourcolor,		0xfce8d8,	CVAR_ARCHIVE);
 CVAR (Color, am_ovwallcolor,		0x00ff00,	CVAR_ARCHIVE);
@@ -141,6 +142,7 @@ CVAR (Color, am_ovthingcolor_monster,	0xe88800,	CVAR_ARCHIVE);
 CVAR (Color, am_ovthingcolor_ncmonster,	0xe88800,	CVAR_ARCHIVE);
 CVAR (Color, am_ovthingcolor_item,		0xe88800,	CVAR_ARCHIVE);
 CVAR (Color, am_ovthingcolor_citem,		0xe88800,	CVAR_ARCHIVE);
+CVAR (Color, am_ovportalcolor,			0x004022,	CVAR_ARCHIVE);
 
 //=============================================================================
 //
@@ -206,6 +208,7 @@ static const char *ColorNames[] = {
 		"IntraTeleportColor", 
 		"InterTeleportColor",
 		"SecretSectorColor",
+		"PortalColor",
 		"AlmostBackgroundColor",
 		NULL
 };
@@ -236,6 +239,7 @@ struct AMColorset
 		IntraTeleportColor, 
 		InterTeleportColor,
 		SecretSectorColor,
+		PortalColor,
 		AlmostBackgroundColor,
 		AM_NUM_COLORS
 	};
@@ -335,7 +339,8 @@ static FColorCVar *cv_standard[] = {
 	&am_lockedcolor,
 	&am_intralevelcolor,
 	&am_interlevelcolor,
-	&am_secretsectorcolor
+	&am_secretsectorcolor,
+	&am_portalcolor
 };
 
 static FColorCVar *cv_overlay[] = {
@@ -360,7 +365,8 @@ static FColorCVar *cv_overlay[] = {
 	&am_ovlockedcolor,
 	&am_ovtelecolor,
 	&am_ovinterlevelcolor,
-	&am_ovsecretsectorcolor
+	&am_ovsecretsectorcolor,
+	&am_ovportalcolor
 };
 
 CCMD(am_restorecolors)
@@ -403,6 +409,7 @@ static unsigned char DoomColors[]= {
 	NOT_USED,		// interteleport
 	NOT_USED,		// secretsector
 	0x10,0x10,0x10,	// almostbackground
+	0x40,0x40,0x40	// portal
 };
 
 static unsigned char StrifeColors[]= {
@@ -429,6 +436,7 @@ static unsigned char StrifeColors[]= {
 	NOT_USED,		// interteleport
 	NOT_USED,		// secretsector
 	0x10,0x10,0x10,	// almostbackground
+	0x40,0x40,0x40	// portal
 };
 
 static unsigned char RavenColors[]= {
@@ -455,6 +463,7 @@ static unsigned char RavenColors[]= {
 	NOT_USED,		// interteleport
 	NOT_USED,		// secretsector
 	0x10,0x10,0x10,	// almostbackground
+	0x50,0x50,0x50	// portal
 };
 
 #undef NOT_USED
@@ -577,6 +586,7 @@ inline fixed_t MTOF(fixed_t x)
 
 static int bigstate = 0;
 static bool textured = 1;	// internal toggle for texture mode
+static int MapPortalGroup;
 
 CUSTOM_CVAR(Bool, am_textured, false, CVAR_ARCHIVE)
 {
@@ -812,6 +822,7 @@ void AM_minOutWindowScale ();
 
 
 CVAR(Bool, am_followplayer, true, CVAR_ARCHIVE)
+CVAR(Bool, am_portaloverlay, true, CVAR_ARCHIVE)
 
 
 CCMD(am_togglefollow)
@@ -1925,6 +1936,12 @@ void AM_drawSubsectors()
 		{
 			continue;
 		}
+
+		if (am_portaloverlay && subsectors[i].render_sector->PortalGroup != MapPortalGroup && subsectors[i].render_sector->PortalGroup != 0)
+		{
+			continue;
+		}
+
 		// Fill the points array from the subsector.
 		points.Resize(subsectors[i].numlines);
 		for (DWORD j = 0; j < subsectors[i].numlines; ++j)
@@ -2389,108 +2406,143 @@ void AM_drawWalls (bool allmap)
 	static mline_t l;
 	int lock, color;
 
-	for (i = 0; i < numlines; i++)
+	int numportalgroups = am_portaloverlay ? Displacements.size : 0;
+
+	for (int p = numportalgroups - 1; p >= -1; p--)
 	{
-		l.a.x = lines[i].v1->x >> FRACTOMAPBITS;
-		l.a.y = lines[i].v1->y >> FRACTOMAPBITS;
-		l.b.x = lines[i].v2->x >> FRACTOMAPBITS;
-		l.b.y = lines[i].v2->y >> FRACTOMAPBITS;
+		if (p == MapPortalGroup) continue;
 
-		if (am_rotate == 1 || (am_rotate == 2 && viewactive))
+
+		for (i = 0; i < numlines; i++)
 		{
-			AM_rotatePoint (&l.a.x, &l.a.y);
-			AM_rotatePoint (&l.b.x, &l.b.y);
-		}
-
-		if (am_cheat != 0 || (lines[i].flags & ML_MAPPED))
-		{
-			if ((lines[i].flags & ML_DONTDRAW) && (am_cheat == 0 || am_cheat >= 4))
+			int pg;
+			
+			if (lines[i].sidedef[0]->Flags & WALLF_POLYOBJ)
 			{
-				if (!am_showallenabled || CheckCheatmode(false))
+				// For polyobjects we must test the surrounding sector to get the proper group.
+				pg = P_PointInSector(lines[i].v1->x + lines[i].dx / 2, lines[i].v1->y + lines[i].dy / 2)->PortalGroup;
+			}
+			else
+			{
+				pg = lines[i].frontsector->PortalGroup;
+			}
+			fixedvec2 offset;
+			bool portalmode = numportalgroups > 0 &&  pg != MapPortalGroup;
+			if (pg == p)
+			{
+				offset = Displacements.getOffset(pg, MapPortalGroup);
+			}
+			else if (p == -1 && (pg == MapPortalGroup || !am_portaloverlay))
+			{
+				offset = { 0, 0 };
+			}
+			else continue;
+
+			l.a.x = (lines[i].v1->x + offset.x) >> FRACTOMAPBITS;
+			l.a.y = (lines[i].v1->y + offset.y) >> FRACTOMAPBITS;
+			l.b.x = (lines[i].v2->x + offset.x) >> FRACTOMAPBITS;
+			l.b.y = (lines[i].v2->y + offset.y) >> FRACTOMAPBITS;
+
+			if (am_rotate == 1 || (am_rotate == 2 && viewactive))
+			{
+				AM_rotatePoint(&l.a.x, &l.a.y);
+				AM_rotatePoint(&l.b.x, &l.b.y);
+			}
+
+			if (am_cheat != 0 || (lines[i].flags & ML_MAPPED))
+			{
+				if ((lines[i].flags & ML_DONTDRAW) && (am_cheat == 0 || am_cheat >= 4))
 				{
-					continue;
+					if (!am_showallenabled || CheckCheatmode(false))
+					{
+						continue;
+					}
+				}
+
+				if (portalmode)
+				{
+					AM_drawMline(&l, AMColors.PortalColor);
+				}
+				else if (AM_CheckSecret(&lines[i]))
+				{
+					// map secret sectors like Boom
+					AM_drawMline(&l, AMColors.SecretSectorColor);
+				}
+				else if (lines[i].flags & ML_SECRET)
+				{ // secret door
+					if (am_cheat != 0 && lines[i].backsector != NULL)
+						AM_drawMline(&l, AMColors.SecretWallColor);
+					else
+						AM_drawMline(&l, AMColors.WallColor);
+				}
+				else if (AM_isTeleportBoundary(lines[i]) && AMColors.isValid(AMColors.IntraTeleportColor))
+				{ // intra-level teleporters
+					AM_drawMline(&l, AMColors.IntraTeleportColor);
+				}
+				else if (AM_isExitBoundary(lines[i]) && AMColors.isValid(AMColors.InterTeleportColor))
+				{ // inter-level/game-ending teleporters
+					AM_drawMline(&l, AMColors.InterTeleportColor);
+				}
+				else if (AM_isLockBoundary(lines[i], &lock))
+				{
+					if (AMColors.displayLocks)
+					{
+						color = P_GetMapColorForLock(lock);
+
+						AMColor c;
+
+						if (color >= 0)	c.FromRGB(RPART(color), GPART(color), BPART(color));
+						else c = AMColors[AMColors.LockedColor];
+
+						AM_drawMline(&l, c);
+					}
+					else
+					{
+						AM_drawMline(&l, AMColors.LockedColor);  // locked special
+					}
+				}
+				else if (am_showtriggerlines
+					&& AMColors.isValid(AMColors.SpecialWallColor)
+					&& AM_isTriggerBoundary(lines[i]))
+				{
+					AM_drawMline(&l, AMColors.SpecialWallColor);	// wall with special non-door action the player can do
+				}
+				else if (lines[i].backsector == NULL)
+				{
+					AM_drawMline(&l, AMColors.WallColor);	// one-sided wall
+				}
+				else if (lines[i].backsector->floorplane
+					!= lines[i].frontsector->floorplane)
+				{
+					AM_drawMline(&l, AMColors.FDWallColor); // floor level change
+				}
+				else if (lines[i].backsector->ceilingplane
+					!= lines[i].frontsector->ceilingplane)
+				{
+					AM_drawMline(&l, AMColors.CDWallColor); // ceiling level change
+				}
+				else if (AM_Check3DFloors(&lines[i]))
+				{
+					AM_drawMline(&l, AMColors.EFWallColor); // Extra floor border
+				}
+				else if (am_cheat > 0 && am_cheat < 4)
+				{
+					AM_drawMline(&l, AMColors.TSWallColor);
 				}
 			}
-
-			if (AM_CheckSecret(&lines[i]))
+			else if (allmap)
 			{
-				// map secret sectors like Boom
-				AM_drawMline(&l, AMColors.SecretSectorColor);
-			}
-			else if (lines[i].flags & ML_SECRET)
-			{ // secret door
-				if (am_cheat != 0 && lines[i].backsector != NULL)
-					AM_drawMline(&l, AMColors.SecretWallColor);
-			    else
-					AM_drawMline(&l, AMColors.WallColor);
-			}
-			else if (AM_isTeleportBoundary(lines[i]) && AMColors.isValid(AMColors.IntraTeleportColor))
-			{ // intra-level teleporters
-				AM_drawMline(&l, AMColors.IntraTeleportColor);
-			}
-			else if (AM_isExitBoundary(lines[i]) && AMColors.isValid(AMColors.InterTeleportColor))
-			{ // inter-level/game-ending teleporters
-				AM_drawMline(&l, AMColors.InterTeleportColor);
-			}
-			else if (AM_isLockBoundary(lines[i], &lock))
-			{
-				if (AMColors.displayLocks)
+				if ((lines[i].flags & ML_DONTDRAW) && (am_cheat == 0 || am_cheat >= 4))
 				{
-					color = P_GetMapColorForLock(lock);
-
-					AMColor c;
-
-					if (color >= 0)	c.FromRGB(RPART(color), GPART(color), BPART(color));
-					else c = AMColors[AMColors.LockedColor];
-
-					AM_drawMline (&l, c);
+					if (!am_showallenabled || CheckCheatmode(false))
+					{
+						continue;
+					}
 				}
-				else
-				{
-					AM_drawMline (&l, AMColors.LockedColor);  // locked special
-				}
-			}
-			else if (am_showtriggerlines
-				&& AMColors.isValid(AMColors.SpecialWallColor)
-				&& AM_isTriggerBoundary(lines[i]))
-			{
-				AM_drawMline(&l, AMColors.SpecialWallColor);	// wall with special non-door action the player can do
-			}
-			else if (lines[i].backsector == NULL)
-			{
-				AM_drawMline(&l, AMColors.WallColor);	// one-sided wall
-			}
-			else if (lines[i].backsector->floorplane
-				  != lines[i].frontsector->floorplane)
-			{
-				AM_drawMline(&l, AMColors.FDWallColor); // floor level change
-			}
-			else if (lines[i].backsector->ceilingplane
-				  != lines[i].frontsector->ceilingplane)
-			{
-				AM_drawMline(&l, AMColors.CDWallColor); // ceiling level change
-			}
-			else if (AM_Check3DFloors(&lines[i]))
-			{
-				AM_drawMline(&l, AMColors.EFWallColor); // Extra floor border
-			}
-			else if (am_cheat > 0 && am_cheat < 4)
-			{
-				AM_drawMline(&l, AMColors.TSWallColor);
+				AM_drawMline(&l, AMColors.NotSeenColor);
 			}
 		}
-		else if (allmap)
-		{
-			if ((lines[i].flags & ML_DONTDRAW) && (am_cheat == 0 || am_cheat >= 4))
-			{
-				if (!am_showallenabled || CheckCheatmode(false))
-				{
-					continue;
-				}
-			}
-			AM_drawMline(&l, AMColors.NotSeenColor);
-		}
-    }
+	}
 }
 
 
@@ -2616,8 +2668,9 @@ void AM_drawPlayers ()
 		mline_t *arrow;
 		int numarrowlines;
 
-		pt.x = players[consoleplayer].camera->X() >> FRACTOMAPBITS;
-		pt.y = players[consoleplayer].camera->Y() >> FRACTOMAPBITS;
+		fixedvec2 pos = am_portaloverlay? players[consoleplayer].camera->GetPortalTransition(players[consoleplayer].viewheight) : (fixedvec2)players[consoleplayer].camera->Pos();
+		pt.x = pos.x >> FRACTOMAPBITS;
+		pt.y = pos.y >> FRACTOMAPBITS;
 		if (am_rotate == 1 || (am_rotate == 2 && viewactive))
 		{
 			angle = ANG90;
@@ -2679,8 +2732,10 @@ void AM_drawPlayers ()
 
 		if (p->mo != NULL)
 		{
-			pt.x = p->mo->X() >> FRACTOMAPBITS;
-			pt.y = p->mo->Y() >> FRACTOMAPBITS;
+			fixedvec3 pos = p->mo->PosRelative(MapPortalGroup);
+			pt.x = pos.x >> FRACTOMAPBITS;
+			pt.y = pos.y >> FRACTOMAPBITS;
+
 			angle = p->mo->angle;
 
 			if (am_rotate == 1 || (am_rotate == 2 && viewactive))
@@ -2711,8 +2766,10 @@ void AM_drawKeys ()
 
 	while ((key = it.Next()) != NULL)
 	{
-		p.x = key->X() >> FRACTOMAPBITS;
-		p.y = key->Y() >> FRACTOMAPBITS;
+		fixedvec3 pos = key->PosRelative(MapPortalGroup);
+		p.x = pos.x >> FRACTOMAPBITS;
+		p.y = pos.y >> FRACTOMAPBITS;
+
 		angle = key->angle;
 
 		if (am_rotate == 1 || (am_rotate == 2 && viewactive))
@@ -2756,8 +2813,9 @@ void AM_drawThings ()
 		{
 			if (am_cheat > 0 || !(t->flags6 & MF6_NOTONAUTOMAP))
 			{
-				p.x = t->X() >> FRACTOMAPBITS;
-				p.y = t->Y() >> FRACTOMAPBITS;
+				fixedvec3 pos = t->PosRelative(MapPortalGroup);
+				p.x = pos.x >> FRACTOMAPBITS;
+				p.y = pos.y >> FRACTOMAPBITS;
 
 				if (am_showthingsprites > 0 && t->sprite > 0)
 				{
@@ -3017,6 +3075,13 @@ void AM_Drawer ()
 	bool allmap = (level.flags2 & LEVEL2_ALLMAP) != 0;
 	bool allthings = allmap && players[consoleplayer].mo->FindInventory(RUNTIME_CLASS(APowerScanner), true) != NULL;
 
+	if (am_portaloverlay)
+	{
+		sector_t *sec;
+		players[consoleplayer].camera->GetPortalTransition(players[consoleplayer].viewheight, &sec);
+		MapPortalGroup = sec->PortalGroup;
+	}
+	else MapPortalGroup = 0;
 	AM_initColors (viewactive);
 
 	if (!viewactive)
diff --git a/src/doomtype.h b/src/doomtype.h
index 22a4d6ffd..db4bc7e5d 100644
--- a/src/doomtype.h
+++ b/src/doomtype.h
@@ -123,6 +123,18 @@ typedef TMap<int, PClassActor *> FClassMap;
 #define NO_SANITIZE
 #endif
 
+#if defined(__GNUC__)
+// With versions of GCC newer than 4.2, it appears it was determined that the
+// cost of an unaligned pointer on PPC was high enough to add padding to the
+// end of packed structs.  For whatever reason __packed__ and pragma pack are
+// handled differently in this regard. Note that this only needs to be applied
+// to types which are used in arrays or sizeof is needed. This also prevents
+// code from taking references to the struct members.
+#define FORCE_PACKED __attribute__((__packed__))
+#else
+#define FORCE_PACKED
+#endif
+
 #include "basictypes.h"
 
 extern bool batchrun;
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index f39a62ab9..11b169e6a 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -4184,12 +4184,12 @@ bool DLevelScript::DoCheckActorTexture(int tid, AActor *activator, int string, b
 
 	if (floor)
 	{
-		actor->Sector->NextLowestFloorAt(actor, actor->Z(), 0, &resultsec, &resffloor);
+		actor->Sector->NextLowestFloorAt(actor->X(), actor->Y(), actor->Z(), 0, actor->MaxStepHeight, &resultsec, &resffloor);
 		secpic = resffloor ? *resffloor->top.texture : resultsec->planes[sector_t::floor].Texture;
 	}
 	else
 	{
-		actor->Sector->NextHighestCeilingAt(actor, actor->Top(), 0, &resultsec, &resffloor);
+		actor->Sector->NextHighestCeilingAt(actor->X(), actor->Y(), actor->Z(), actor->Top(), 0, &resultsec, &resffloor);
 		secpic = resffloor ? *resffloor->bottom.texture : resultsec->planes[sector_t::ceiling].Texture;
 	}
 	return tex == TexMan[secpic];
@@ -5946,8 +5946,8 @@ doplaysound:			if (funcIndex == ACSF_PlayActorSound)
 				reference = SingleActorFromTID(tid_dest, activator);
 			}
 
-			// If there is no actor to warp to, fail.
-			if (!reference)
+			// If there is no activator or actor to warp to, fail.
+			if (activator == NULL || !reference)
 				return false;
 
 			if (P_Thing_Warp(activator, reference, xofs, yofs, zofs, angle, flags, heightoffset, radiusoffset, pitch))
diff --git a/src/p_map.cpp b/src/p_map.cpp
index ca8b7b751..8c9b21055 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -290,7 +290,7 @@ void P_GetFloorCeilingZ(FCheckPosition &tmf, int flags)
 	sector_t *sec = (!(flags & FFCF_SAMESECTOR) || tmf.thing->Sector == NULL)? P_PointInSector(tmf.x, tmf.y) : tmf.sector;
 	F3DFloor *ffc, *fff;
 
-	tmf.ceilingz = sec->NextHighestCeilingAt(tmf.x, tmf.y, tmf.z + tmf.thing->height, flags, &tmf.ceilingsector, &ffc);
+	tmf.ceilingz = sec->NextHighestCeilingAt(tmf.x, tmf.y, tmf.z, tmf.z + tmf.thing->height, flags, &tmf.ceilingsector, &ffc);
 	tmf.floorz = tmf.dropoffz = sec->NextLowestFloorAt(tmf.x, tmf.y, tmf.z, flags, tmf.thing->MaxStepHeight, &tmf.floorsector, &fff);
 
 	if (fff)
@@ -997,7 +997,7 @@ bool PIT_CheckLine(FMultiBlockLinesIterator &mit, FMultiBlockLinesIterator::Chec
 		spec.oldrefpos = tm.thing->PosRelative(ld);
 		spechit.Push(spec);
 	}
-	if (ld->portalindex != UINT_MAX)
+	if (ld->isLinePortal())
 	{
 		spec.line = ld;
 		spec.refpos = cres.position;
@@ -3793,7 +3793,7 @@ struct aim_t
 		intercept_t *in;
 
 		if (aimdebug)
-			Printf("Start AimTraverse, start = %f,%f,%f, vect = %f,%f,%f\n",
+			Printf("Start AimTraverse, start = %f,%f,%f, vect = %f,%f\n",
 				startpos.x / 65536., startpos.y / 65536., startpos.z / 65536.,
 				aimtrace.x / 65536., aimtrace.y / 65536.);
 		
diff --git a/src/p_maputl.cpp b/src/p_maputl.cpp
index b55989c97..2670ead2c 100644
--- a/src/p_maputl.cpp
+++ b/src/p_maputl.cpp
@@ -1980,6 +1980,10 @@ int P_VanillaPointOnDivlineSide(fixed_t x, fixed_t y, const divline_t* line)
 
 sector_t *P_PointInSectorBuggy(fixed_t x, fixed_t y)
 {
+	// single subsector is a special case
+	if (numgamenodes == 0)
+		return gamesubsectors->sector;
+
 	node_t *node = gamenodes + numgamenodes - 1;
 
 	do
diff --git a/src/p_sectors.cpp b/src/p_sectors.cpp
index d9cd733cb..27c8493ea 100644
--- a/src/p_sectors.cpp
+++ b/src/p_sectors.cpp
@@ -932,7 +932,7 @@ fixed_t sector_t::LowestFloorAt(fixed_t x, fixed_t y, sector_t **resultsec)
 }
 
 
-fixed_t sector_t::NextHighestCeilingAt(fixed_t x, fixed_t y, fixed_t z, int flags, sector_t **resultsec, F3DFloor **resultffloor)
+fixed_t sector_t::NextHighestCeilingAt(fixed_t x, fixed_t y, fixed_t bottomz, fixed_t topz, int flags, sector_t **resultsec, F3DFloor **resultffloor)
 {
 	sector_t *sec = this;
 	fixed_t planeheight = FIXED_MIN;
@@ -943,14 +943,20 @@ fixed_t sector_t::NextHighestCeilingAt(fixed_t x, fixed_t y, fixed_t z, int flag
 		fixed_t realceil = sec->ceilingplane.ZatPoint(x, y);
 		for (int i = sec->e->XFloor.ffloors.Size() - 1; i >= 0; --i)
 		{
-			F3DFloor *ff = sec->e->XFloor.ffloors[i];
+			F3DFloor *rover = sec->e->XFloor.ffloors[i];
+			if (!(rover->flags & FF_SOLID) || !(rover->flags & FF_EXISTS)) continue;
 
-			fixed_t ffz = ff->bottom.plane->ZatPoint(x, y);
-			if (ffz < realceil && ((ff->flags & (FF_EXISTS | FF_SOLID)) == (FF_EXISTS | FF_SOLID) && z <= ffz))
-			{ // This floor is above our eyes.
+			fixed_t ff_bottom = rover->bottom.plane->ZatPoint(x, y);
+			fixed_t ff_top = rover->top.plane->ZatPoint(x, y);
+
+			fixed_t delta1 = bottomz - (ff_bottom + ((ff_top - ff_bottom) / 2));
+			fixed_t delta2 = topz - (ff_bottom + ((ff_top - ff_bottom) / 2));
+
+			if (ff_bottom < realceil && abs(delta1) >= abs(delta2))
+			{ 
 				if (resultsec) *resultsec = sec;
-				if (resultffloor) *resultffloor = ff;
-				return ffz;
+				if (resultffloor) *resultffloor = rover;
+				return ff_bottom;
 			}
 		}
 		if ((flags & FFCF_NOPORTALS) || sec->PortalBlocksMovement(ceiling) || planeheight >= sec->SkyBoxes[ceiling]->threshold)
diff --git a/src/p_trace.cpp b/src/p_trace.cpp
index 2dec3d9d5..1de5e7059 100644
--- a/src/p_trace.cpp
+++ b/src/p_trace.cpp
@@ -342,7 +342,7 @@ void FTraceInfo::Setup3DFloors()
 					{
 						CurSector->floorplane = *rover->top.plane;
 						CurSector->SetTexture(sector_t::floor, *rover->top.texture, false);
-						CurSector->SkyBoxes[sector_t::floor] == NULL;
+						CurSector->SkyBoxes[sector_t::floor] = nullptr;
 						bf = ff_top;
 					}
 				}
@@ -354,7 +354,7 @@ void FTraceInfo::Setup3DFloors()
 						CurSector->ceilingplane = *rover->bottom.plane;
 						CurSector->SetTexture(sector_t::ceiling, *rover->bottom.texture, false);
 						bc = ff_bottom;
-						CurSector->SkyBoxes[sector_t::ceiling] == NULL;
+						CurSector->SkyBoxes[sector_t::ceiling] = nullptr;
 					}
 				}
 				else
@@ -364,7 +364,7 @@ void FTraceInfo::Setup3DFloors()
 					{
 						CurSector->floorplane = *rover->bottom.plane;
 						CurSector->SetTexture(sector_t::floor, *rover->bottom.texture, false);
-						CurSector->SkyBoxes[sector_t::floor] == NULL;
+						CurSector->SkyBoxes[sector_t::floor] = nullptr;
 						bf = ff_bottom;
 					}
 
@@ -372,7 +372,7 @@ void FTraceInfo::Setup3DFloors()
 					{
 						CurSector->ceilingplane = *rover->top.plane;
 						CurSector->SetTexture(sector_t::ceiling, *rover->top.texture, false);
-						CurSector->SkyBoxes[sector_t::ceiling] == NULL;
+						CurSector->SkyBoxes[sector_t::ceiling] = nullptr;
 						bc = ff_top;
 					}
 					inshootthrough = false;
diff --git a/src/portal.cpp b/src/portal.cpp
index a9dd40487..de2d1d14b 100644
--- a/src/portal.cpp
+++ b/src/portal.cpp
@@ -955,6 +955,7 @@ void P_CreateLinkedPortals()
 			}
 		}
 	}
+	id = 1;
 	if (orgs.Size() != 0)
 	{
 		for (int i = 0; i < numsectors; i++)
diff --git a/src/posix/cocoa/i_common.h b/src/posix/cocoa/i_common.h
index beff4a33d..4a558cf24 100644
--- a/src/posix/cocoa/i_common.h
+++ b/src/posix/cocoa/i_common.h
@@ -149,6 +149,8 @@ static const NSOpenGLPixelFormatAttribute NSOpenGLPFAAllowOfflineRenderers = NSO
 - (void)setCollectionBehavior:(NSUInteger)collectionBehavior;
 @end
 
+typedef NSUInteger NSWindowCollectionBehavior;
+
 #endif // prior to 10.5
 
 
diff --git a/src/posix/cocoa/i_main.mm b/src/posix/cocoa/i_main.mm
index 2f65254a9..5729a3716 100644
--- a/src/posix/cocoa/i_main.mm
+++ b/src/posix/cocoa/i_main.mm
@@ -67,7 +67,6 @@ EXTERN_CVAR(Bool, fullscreen   )
 
 // ---------------------------------------------------------------------------
 
-
 namespace
 {
 
@@ -78,6 +77,9 @@ void      (*TermFuncs[MAX_TERMS])();
 const char *TermNames[MAX_TERMS];
 size_t      NumTerms;
 
+} // unnamed namespace
+
+// Expose this for i_main_except.cpp
 void call_terms()
 {
 	while (NumTerms > 0)
@@ -86,8 +88,6 @@ void call_terms()
 	}
 }
 
-} // unnamed namespace
-
 
 void addterm(void (*func)(), const char *name)
 {
@@ -133,6 +133,41 @@ void Mac_I_FatalError(const char* const message)
 DArgs* Args; // command line arguments
 
 
+// Newer versions of GCC than 4.2 have a bug with C++ exceptions in Objective-C++ code.
+// To work around we'll implement the try and catch in standard C++.
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61759
+void OriginalMainExcept(int argc, char** argv);
+void OriginalMainTry(int argc, char** argv)
+{
+	Args = new DArgs(argc, argv);
+
+	/*
+	 killough 1/98:
+
+	 This fixes some problems with exit handling
+	 during abnormal situations.
+
+	 The old code called I_Quit() to end program,
+	 while now I_Quit() is installed as an exit
+	 handler and exit() is called to exit, either
+	 normally or abnormally. Seg faults are caught
+	 and the error handler is used, to prevent
+	 being left in graphics mode or having very
+	 loud SFX noise because the sound card is
+	 left in an unstable state.
+	 */
+
+	atexit(call_terms);
+	atterm(I_Quit);
+
+	NSString* exePath = [[NSBundle mainBundle] executablePath];
+	progdir = [[exePath stringByDeletingLastPathComponent] UTF8String];
+	progdir += "/";
+
+	C_InitConsole(80 * 8, 25 * 8, false);
+	D_DoomMain();
+}
+
 namespace
 {
 
@@ -151,7 +186,6 @@ void NewFailure()
 	I_FatalError("Failed to allocate memory from system heap");
 }
 
-
 int OriginalMain(int argc, char** argv)
 {
 	printf(GAMENAME" %s - %s - Cocoa version\nCompiled on %s\n\n",
@@ -174,53 +208,7 @@ int OriginalMain(int argc, char** argv)
 	vid_vsync     = true;
 	fullscreen    = true;
 
-	try
-	{
-		Args = new DArgs(argc, argv);
-
-		/*
-		 killough 1/98:
-
-		 This fixes some problems with exit handling
-		 during abnormal situations.
-
-		 The old code called I_Quit() to end program,
-		 while now I_Quit() is installed as an exit
-		 handler and exit() is called to exit, either
-		 normally or abnormally. Seg faults are caught
-		 and the error handler is used, to prevent
-		 being left in graphics mode or having very
-		 loud SFX noise because the sound card is
-		 left in an unstable state.
-		 */
-
-		atexit(call_terms);
-		atterm(I_Quit);
-
-		NSString* exePath = [[NSBundle mainBundle] executablePath];
-		progdir = [[exePath stringByDeletingLastPathComponent] UTF8String];
-		progdir += "/";
-
-		C_InitConsole(80 * 8, 25 * 8, false);
-		D_DoomMain();
-	}
-	catch(const CDoomError& error)
-	{
-		const char* const message = error.GetMessage();
-
-		if (NULL != message)
-		{
-			fprintf(stderr, "%s\n", message);
-			Mac_I_FatalError(message);
-		}
-
-		exit(-1);
-	}
-	catch(...)
-	{
-		call_terms();
-		throw;
-	}
+	OriginalMainExcept(argc, argv);
 
 	return 0;
 }
diff --git a/src/posix/cocoa/i_main_except.cpp b/src/posix/cocoa/i_main_except.cpp
new file mode 100644
index 000000000..8a095f2a0
--- /dev/null
+++ b/src/posix/cocoa/i_main_except.cpp
@@ -0,0 +1,34 @@
+// Workaround for GCC Objective-C++ with C++ exceptions bug.
+
+#include "doomerrors.h"
+#include <stdlib.h>
+
+// Import some functions from i_main.mm
+void call_terms();
+void Mac_I_FatalError(const char* const message);
+void OriginalMainTry(int argc, char** argv);
+
+void OriginalMainExcept(int argc, char** argv)
+{
+	try
+	{
+		OriginalMainTry(argc, argv);
+	}
+	catch(const CDoomError& error)
+	{
+		const char* const message = error.GetMessage();
+
+		if (NULL != message)
+		{
+			fprintf(stderr, "%s\n", message);
+			Mac_I_FatalError(message);
+		}
+
+		exit(-1);
+	}
+	catch(...)
+	{
+		call_terms();
+		throw;
+	}
+}
diff --git a/src/r_defs.h b/src/r_defs.h
index c1e6b5d75..ae6409edd 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -873,19 +873,9 @@ struct sector_t
 		return LowestFloorAt(a->X(), a->Y(), resultsec);
 	}
 
-	fixed_t NextHighestCeilingAt(fixed_t x, fixed_t y, fixed_t z, int flags = 0, sector_t **resultsec = NULL, F3DFloor **resultffloor = NULL);
+	fixed_t NextHighestCeilingAt(fixed_t x, fixed_t y, fixed_t bottomz, fixed_t topz, int flags = 0, sector_t **resultsec = NULL, F3DFloor **resultffloor = NULL);
 	fixed_t NextLowestFloorAt(fixed_t x, fixed_t y, fixed_t z, int flags = 0, fixed_t steph = 0, sector_t **resultsec = NULL, F3DFloor **resultffloor = NULL);
 
-	fixed_t NextHighestCeilingAt(AActor *a, fixed_t z, int flags = 0, sector_t **resultsec = NULL, F3DFloor **resultffloor = NULL)
-	{
-		return NextHighestCeilingAt(a->X(), a->Y(), z, flags, resultsec, resultffloor);
-	}
-
-	fixed_t NextLowestFloorAt(AActor *a, fixed_t z, int flags, sector_t **resultsec = NULL, F3DFloor **resultffloor = NULL)
-	{
-		return NextLowestFloorAt(a->X(), a->Y(), z, flags, a->MaxStepHeight, resultsec, resultffloor);
-	}
-
 	// Member variables
 	fixed_t		CenterFloor () const { return floorplane.ZatPoint (centerspot); }
 	fixed_t		CenterCeiling () const { return ceilingplane.ZatPoint (centerspot); }
diff --git a/src/sound/music_dumb.cpp b/src/sound/music_dumb.cpp
index 31f42b319..fe1fbbb76 100644
--- a/src/sound/music_dumb.cpp
+++ b/src/sound/music_dumb.cpp
@@ -100,14 +100,14 @@ typedef struct tagITFILEHEADER
 	DWORD reserved2;
 	BYTE chnpan[64];
 	BYTE chnvol[64];
-} ITFILEHEADER, *PITFILEHEADER;
+} FORCE_PACKED ITFILEHEADER, *PITFILEHEADER;
 
 typedef struct MODMIDICFG
 {
 	char szMidiGlb[9*32];      // changed from CHAR
 	char szMidiSFXExt[16*32];  // changed from CHAR
 	char szMidiZXXExt[128*32]; // changed from CHAR
-} MODMIDICFG, *LPMODMIDICFG;
+} FORCE_PACKED MODMIDICFG, *LPMODMIDICFG;
 
 #pragma pack()
 
diff --git a/src/textures/pcxtexture.cpp b/src/textures/pcxtexture.cpp
index 125898cce..0ec5d2933 100644
--- a/src/textures/pcxtexture.cpp
+++ b/src/textures/pcxtexture.cpp
@@ -72,7 +72,7 @@ struct PCXHeader
 
   BYTE padding[54];
 
-};
+} FORCE_PACKED;
 #pragma pack()
 
 //==========================================================================
diff --git a/src/w_zip.h b/src/w_zip.h
index 16fb7acc7..4f51a13cc 100644
--- a/src/w_zip.h
+++ b/src/w_zip.h
@@ -13,7 +13,7 @@ struct FZipEndOfCentralDirectory
 	DWORD	DirectorySize;
 	DWORD	DirectoryOffset;
 	WORD	ZipCommentLength;
-};
+} FORCE_PACKED;
 
 // FZipFileInfo
 struct FZipCentralDirectoryInfo
@@ -36,7 +36,7 @@ struct FZipCentralDirectoryInfo
 	DWORD	ExternalAttributes;
 	DWORD	LocalHeaderOffset;
 	// file name and other variable length info follows
-};
+} FORCE_PACKED;
 
 // FZipLocalHeader
 struct FZipLocalFileHeader
@@ -53,7 +53,7 @@ struct FZipLocalFileHeader
 	WORD	NameLength;
 	WORD	ExtraLength;
 	// file name and other variable length info follows
-};
+} FORCE_PACKED;
 
 
 #pragma pack()
diff --git a/tools/zipdir/zipdir.c b/tools/zipdir/zipdir.c
index cb43f5f82..e21b9ba13 100644
--- a/tools/zipdir/zipdir.c
+++ b/tools/zipdir/zipdir.c
@@ -60,6 +60,17 @@
 #define __cdecl
 #endif
 
+#ifdef __GNUC__
+// With versions of GCC newer than 4.2, it appears it was determined that the
+// cost of an unaligned pointer on PPC was high enough to add padding to the
+// end of packed structs.  For whatever reason __packed__ and pragma pack are
+// handled differently in this regard. Note that this only needs to be applied
+// to types which are used in arrays.
+#define FORCE_PACKED __attribute__((__packed__))
+#else
+#define FORCE_PACKED
+#endif
+
 #ifndef __BIG_ENDIAN__
 #define MAKE_ID(a,b,c,d)	((a)|((b)<<8)|((c)<<16)|((d)<<24))
 #define LittleShort(x)		(x)
@@ -150,7 +161,7 @@ typedef struct
 	UINT32	UncompressedSize;			// 22
 	WORD	NameLength;					// 26
 	WORD	ExtraLength;				// 28
-} LocalFileHeader;
+} FORCE_PACKED LocalFileHeader;
 
 typedef struct
 {
@@ -171,7 +182,7 @@ typedef struct
 	WORD	InternalAttributes;
 	UINT32	ExternalAttributes;
 	UINT32	LocalHeaderOffset;
-} CentralDirectoryEntry;
+} FORCE_PACKED CentralDirectoryEntry;
 
 typedef struct
 {
@@ -183,7 +194,7 @@ typedef struct
 	UINT32	DirectorySize;
 	UINT32	DirectoryOffset;
 	WORD	ZipCommentLength;
-} EndOfCentralDirectory;
+} FORCE_PACKED EndOfCentralDirectory;
 //#pragma pack(pop)
 
 // EXTERNAL FUNCTION PROTOTYPES --------------------------------------------
diff --git a/wadsrc/static/language.eng b/wadsrc/static/language.eng
index 11c5b8f0a..ca27bf80a 100644
--- a/wadsrc/static/language.eng
+++ b/wadsrc/static/language.eng
@@ -108,4 +108,3 @@ CMPTMNU_SECTORSOUNDS = "Sector sounds use centre as source";
 OPTVAL_MAPDEFINEDCOLORSONLY = "Map defined colours only";
 C_GRAY = "\ccgrey";
 C_DARKGRAY = "\cudark grey";
-MNU_COLORPICKER = "SELECT COLOUR";
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index 6f1ef060d..e76df2f39 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -1880,6 +1880,7 @@ AUTOMAPMNU_DRAWMAPBACK			= "Draw map background";
 AUTOMAPMNU_SHOWKEYS				= "Show keys (cheat)";
 AUTOMAPMNU_SHOWTRIGGERLINES		= "Show trigger lines";
 AUTOMAPMNU_SHOWTHINGSPRITES		= "Show things as sprites";
+AUTOMAPMNU_PTOVERLAY			= "Overlay portals";
 
 // Automap Controls
 MAPCNTRLMNU_TITLE 			= "CUSTOMIZE MAP CONTROLS";
@@ -1925,6 +1926,7 @@ MAPCOLORMNU_ITEMCOLOR 					= "Items";
 MAPCOLORMNU_COUNTITEMCOLOR 				= "Count Items";
 MAPCOLORMNU_OVERLAY 					= "Overlay Mode";
 MAPCOLORMNU_OVCHEATMODE 				= "Overlay Cheat Mode";
+MAPCOLORMNU_PORTAL						= "Portal Overlays";
 
 // Message Options
 MSGMNU_TITLE				= "MESSAGES";
diff --git a/wadsrc/static/menudef.txt b/wadsrc/static/menudef.txt
index c07ae9411..cf01173e6 100644
--- a/wadsrc/static/menudef.txt
+++ b/wadsrc/static/menudef.txt
@@ -982,6 +982,7 @@ OptionMenu AutomapOptions
 	Option "$AUTOMAPMNU_OVERLAY",				"am_overlay", "OverlayTypes"
 	Option "$AUTOMAPMNU_TEXTURED",				"am_textured", "OnOff"
 	Option "$AUTOMAPMNU_FOLLOW",				"am_followplayer", "OnOff"
+	Option "$AUTOMAPMNU_PTOVERLAY",				"am_portaloverlay", "OnOff"
 	StaticText " "
 	Option "$AUTOMAPMNU_SHOWITEMS",				"am_showitems", "OnOff"
 	Option "$AUTOMAPMNU_SHOWMONSTERS",			"am_showmonsters", "OnOff"
@@ -1048,6 +1049,7 @@ OptionMenu MapColorMenu
 	ColorPicker "$MAPCOLORMNU_INTERLEVELCOLOR",			"am_interlevelcolor"	
 	ColorPicker "$MAPCOLORMNU_SECRETSECTORCOLOR",		"am_secretsectorcolor"	
 	ColorPicker "$MAPCOLORMNU_SPECIALWALLCOLOR",		"am_specialwallcolor"
+	ColorPicker "$MAPCOLORMNU_PORTAL",					"am_portalcolor"
 	StaticText " "
 	StaticText "$MAPCOLORMNU_CHEATMODE", 1
 	ColorPicker "$MAPCOLORMNU_TSWALLCOLOR",				"am_tswallcolor"		
@@ -1071,6 +1073,7 @@ OptionMenu MapColorMenu
 	ColorPicker "$MAPCOLORMNU_INTERLEVELCOLOR",			"am_ovinterlevelcolor"	
 	ColorPicker "$MAPCOLORMNU_SECRETSECTORCOLOR",		"am_ovsecretsectorcolor"	
 	ColorPicker "$MAPCOLORMNU_SPECIALWALLCOLOR",		"am_ovspecialwallcolor"
+	ColorPicker "$MAPCOLORMNU_PORTAL",					"am_ovportalcolor"
 	StaticText " "
 	StaticText "$MAPCOLORMNU_OVCHEATMODE", 1
 	ColorPicker "$MAPCOLORMNU_TSWALLCOLOR",				"am_ovotherwallscolor"