diff --git a/src/actor.h b/src/actor.h
index 043f07ae5f..be3f28ec61 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -401,6 +401,7 @@ enum ActorFlag7
 enum ActorFlag8
 {
 	MF8_FRIGHTENING		= 0x00000001,	// for those moments when halloween just won't do
+	MF8_INSCROLLSEC		= 0x00000002,	// actor is partially inside a scrolling sector
 };
 
 // --- mobj.renderflags ---
diff --git a/src/gl/scene/gl_flats.cpp b/src/gl/scene/gl_flats.cpp
index c7ab0eeb28..98f5afa801 100644
--- a/src/gl/scene/gl_flats.cpp
+++ b/src/gl/scene/gl_flats.cpp
@@ -750,6 +750,7 @@ void GLFlat::ProcessSector(sector_t * frontsector)
 		// is no longer necessary.
 
 		ceiling = true;
+		Colormap = frontsector->Colormap;
 		for (k = 0; k < (int)x.ffloors.Size(); k++)
 		{
 			rover = x.ffloors[k];
diff --git a/src/gl/system/gl_interface.cpp b/src/gl/system/gl_interface.cpp
index 308d741bb3..e24ac553b2 100644
--- a/src/gl/system/gl_interface.cpp
+++ b/src/gl/system/gl_interface.cpp
@@ -213,6 +213,16 @@ void gl_LoadExtensions()
 			gl.glslversion = 0;
 			gl.flags |= RFL_NO_CLIP_PLANES;
 		}
+		else if (gl.glslversion < 1.4f && !CheckExtension("GL_ARB_uniform_buffer_object"))
+		{
+			// Some old ATI drivers report OpenGL 3.1 with GLSL version 1.3 and no support for uniform buffers.
+			// We have no choice but to force them down to OpenGL 2.x.
+			gl.legacyMode = true;
+			gl.lightmethod = LM_LEGACY;
+			gl.buffermethod = BM_LEGACY;
+			gl.glslversion = 0;
+			gl.flags |= RFL_NO_CLIP_PLANES;
+		}
 		else
 		{
 			gl.legacyMode = false;
diff --git a/src/p_effect.cpp b/src/p_effect.cpp
index 81a1bc5d62..7163b7548d 100644
--- a/src/p_effect.cpp
+++ b/src/p_effect.cpp
@@ -814,7 +814,7 @@ void P_DrawRailTrail(AActor *source, TArray<SPortalHit> &portalhits, int color1,
 	// Create the inner trail.
 	if (color2 != -1 && r_rail_trailsparsity > 0 && spawnclass == NULL)
 	{
-		double stepsize = 3 * r_rail_spiralsparsity * sparsity;
+		double stepsize = 3 * r_rail_trailsparsity * sparsity;
 		int trail_steps = xs_FloorToInt(steps * r_rail_trailsparsity / sparsity);
 
 		color2 = color2 == 0 ? -1 : ParticleColor(color2);
@@ -891,7 +891,7 @@ void P_DrawRailTrail(AActor *source, TArray<SPortalHit> &portalhits, int color1,
 		if (sparsity < 1)
 			sparsity = 32;
 
-		double stepsize = 3 * r_rail_spiralsparsity * sparsity;
+		double stepsize = sparsity;
 		int trail_steps = (int)((steps * 3) / sparsity);
 		DVector3 diff(0, 0, 0);
 
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index c2aa09682f..13af2837c4 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -4098,6 +4098,7 @@ void AActor::Tick ()
 			CheckPortalTransition(false);
 			LinkToWorld(&ctx);
 		}
+		flags8 &= ~MF8_INSCROLLSEC;
 	}
 	else
 	{
@@ -4250,12 +4251,16 @@ void AActor::Tick ()
 
 		// [RH] Consider carrying sectors here
 		DVector2 cumm(0, 0);
-		if ((level.Scrolls.Size() != 0 || player != NULL) && !(flags & MF_NOCLIP) && !(flags & MF_NOSECTOR))
+
+		if ((((flags8 & MF8_INSCROLLSEC) && level.Scrolls.Size() > 0) || player != NULL) && !(flags & MF_NOCLIP) && !(flags & MF_NOSECTOR))
 		{
 			double height, waterheight;	// killough 4/4/98: add waterheight
 			const msecnode_t *node;
 			int countx, county;
 
+			// Clear the flag for the next frame.
+			flags8 &= ~MF8_INSCROLLSEC;
+
 			// killough 3/7/98: Carry things on floor
 			// killough 3/20/98: use new sector list which reflects true members
 			// killough 3/27/98: fix carrier bug
@@ -5079,6 +5084,8 @@ AActor *AActor::StaticSpawn (PClassActor *type, const DVector3 &pos, replace_t a
 	{
 		level.total_secrets++;
 	}
+	// force scroller check in the first tic.
+	actor->flags8 |= MF8_INSCROLLSEC;
 	return actor;
 }
 
diff --git a/src/p_scroll.cpp b/src/p_scroll.cpp
index f2661a2a1d..d8666d9a7e 100644
--- a/src/p_scroll.cpp
+++ b/src/p_scroll.cpp
@@ -256,6 +256,11 @@ void DScroller::Tick ()
 		case EScroll::sc_carry:
 			level.Scrolls[m_Affectee].X += dx;
 			level.Scrolls[m_Affectee].Y += dy;
+			// mark all potentially affected things here so that the very expensive calculation loop in AActor::Tick does not need to run for actors which do not touch a scrolling sector.
+			for (auto n = level.sectors[m_Affectee].touching_thinglist; n; n = n->m_snext)
+			{
+				n->m_thing->flags8 |= MF8_INSCROLLSEC;
+			}
 			break;
 
 		case EScroll::sc_carry_ceiling:       // to be added later
diff --git a/src/posix/cocoa/i_main.mm b/src/posix/cocoa/i_main.mm
index d8fef49324..1c418b91b4 100644
--- a/src/posix/cocoa/i_main.mm
+++ b/src/posix/cocoa/i_main.mm
@@ -32,6 +32,7 @@
  */
 
 #include "i_common.h"
+#include "s_sound.h"
 
 #include <sys/sysctl.h>
 #include <unistd.h>
@@ -125,6 +126,7 @@ void popterm()
 void Mac_I_FatalError(const char* const message)
 {
 	I_SetMainWindowVisible(false);
+	S_StopMusic(true);
 
 	FConsoleWindow::GetInstance().ShowFatalError(message);
 }
diff --git a/src/scripting/vm/vmexec.cpp b/src/scripting/vm/vmexec.cpp
index 0bad8c0554..eb212a6466 100644
--- a/src/scripting/vm/vmexec.cpp
+++ b/src/scripting/vm/vmexec.cpp
@@ -104,14 +104,6 @@ void ThrowVMException(VMException *x);
 	if (a == NULL) { ThrowAbortException(x, nullptr); } \
 	ptr = (VM_SBYTE *)a + o
 
-static const VM_UWORD ZapTable[16] =
-{
-	0x00000000, 0x000000FF, 0x0000FF00, 0x0000FFFF,
-	0x00FF0000, 0x00FF00FF, 0x00FFFF00, 0x00FFFFFF,
-	0xFF000000, 0xFF0000FF, 0xFF00FF00, 0xFF00FFFF,
-	0xFFFF0000, 0xFFFF00FF, 0xFFFFFF00, 0xFFFFFFFF
-};
-
 #ifdef NDEBUG
 #define WAS_NDEBUG 1
 #else
diff --git a/src/scripting/vm/vmexec.h b/src/scripting/vm/vmexec.h
index 452414c99f..7e8a53a6a9 100644
--- a/src/scripting/vm/vmexec.h
+++ b/src/scripting/vm/vmexec.h
@@ -1195,28 +1195,6 @@ static int Exec(VMFrameStack *stack, const VMOP *pc, VMReturn *ret, int numret)
 		reg.d[a] = ~reg.d[B];
 		NEXTOP;
 
-	OP(SEXT):
-		ASSERTD(a); ASSERTD(B);
-		reg.d[a] = (VM_SWORD)(reg.d[B] << C) >> C;
-		NEXTOP;
-
-	OP(ZAP_R):
-		ASSERTD(a); ASSERTD(B); ASSERTD(C);
-		reg.d[a] = reg.d[B] & ZapTable[(reg.d[C] & 15) ^ 15];
-		NEXTOP;
-	OP(ZAP_I):
-		ASSERTD(a); ASSERTD(B);
-		reg.d[a] = reg.d[B] & ZapTable[(C & 15) ^ 15];
-		NEXTOP;
-	OP(ZAPNOT_R):
-		ASSERTD(a); ASSERTD(B); ASSERTD(C);
-		reg.d[a] = reg.d[B] & ZapTable[reg.d[C] & 15];
-		NEXTOP;
-	OP(ZAPNOT_I):
-		ASSERTD(a); ASSERTD(B);
-		reg.d[a] = reg.d[B] & ZapTable[C & 15];
-		NEXTOP;
-
 	OP(EQ_R):
 		ASSERTD(B); ASSERTD(C);
 		CMPJMP(reg.d[B] == reg.d[C]);
diff --git a/src/scripting/vm/vmops.h b/src/scripting/vm/vmops.h
index dac9075805..fb0a9e50e4 100644
--- a/src/scripting/vm/vmops.h
+++ b/src/scripting/vm/vmops.h
@@ -174,11 +174,6 @@ xx(MAX_RK,		max,	RIRIKI,		MAX_RR,	4, REGT_INT),
 xx(ABS,			abs,	RIRI,		NOP,	0, 0),			// dA = abs(dB)
 xx(NEG,			neg,	RIRI,		NOP,	0, 0),			// dA = -dB
 xx(NOT,			not,	RIRI,		NOP,	0, 0),			// dA = ~dB
-xx(SEXT,		sext,	RIRII8,		NOP,	0, 0),		// dA = dB, sign extended by shifting left then right by C
-xx(ZAP_R,		zap,	RIRIRI,		NOP,	0, 0),		// dA = dB, with bytes zeroed where bits in C/dC are one
-xx(ZAP_I,		zap,	RIRII8,		NOP,	0, 0),
-xx(ZAPNOT_R,	zapnot,	RIRIRI,		NOP,	0, 0),		// dA = dB, with bytes zeroed where bits in C/dC are zero
-xx(ZAPNOT_I,	zapnot,	RIRII8,		NOP,	0, 0),
 xx(EQ_R,		beq,	CIRR,		NOP,	0, 0),			// if ((dB == dkC) != A) then pc++
 xx(EQ_K,		beq,	CIRK,		EQ_R,	4, REGT_INT),
 xx(LT_RR,		blt,	CIRR,		NOP,	0, 0),			// if ((dkB < dkC) != A) then pc++
diff --git a/src/win32/i_main.cpp b/src/win32/i_main.cpp
index c82fb19694..4ae1595ef3 100644
--- a/src/win32/i_main.cpp
+++ b/src/win32/i_main.cpp
@@ -81,6 +81,7 @@
 #include "doomstat.h"
 #include "r_utility.h"
 #include "g_levellocals.h"
+#include "s_sound.h"
 
 #include "stats.h"
 #include "st_start.h"
@@ -1060,6 +1061,7 @@ void DoMain (HINSTANCE hInstance)
 	{
 		I_ShutdownGraphics ();
 		RestoreConView ();
+		S_StopMusic(true);
 		I_FlushBufferedConsoleStuff();
 		if (error.GetMessage ())
 		{