diff --git a/src/g_statusbar/shared_sbar.cpp b/src/g_statusbar/shared_sbar.cpp
index 8b6b23170..fe4028091 100644
--- a/src/g_statusbar/shared_sbar.cpp
+++ b/src/g_statusbar/shared_sbar.cpp
@@ -1700,6 +1700,7 @@ DEFINE_ACTION_FUNCTION(DBaseStatusBar, DrawTexture)
 	PARAM_FLOAT_DEF(h);
 	PARAM_FLOAT_DEF(scaleX);
 	PARAM_FLOAT_DEF(scaleY);
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	self->DrawGraphic(FSetTextureID(texid), x, y, flags, alpha, w, h, scaleX, scaleY);
 	return 0;
 }
@@ -1716,6 +1717,7 @@ DEFINE_ACTION_FUNCTION(DBaseStatusBar, DrawImage)
 	PARAM_FLOAT_DEF(h);
 	PARAM_FLOAT_DEF(scaleX);
 	PARAM_FLOAT_DEF(scaleY);
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	self->DrawGraphic(TexMan.CheckForTexture(texid, FTexture::TEX_Any), x, y, flags, alpha, w, h, scaleX, scaleY);
 	return 0;
 }
@@ -1908,6 +1910,7 @@ DEFINE_ACTION_FUNCTION(DBaseStatusBar, DrawString)
 	PARAM_INT_DEF(wrapwidth);
 	PARAM_INT_DEF(linespacing);
 
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 
 	// resolve auto-alignment before making any adjustments to the position values.
 	if (!(flags & DI_SCREEN_MANUAL_ALIGN))
@@ -2012,6 +2015,7 @@ DEFINE_ACTION_FUNCTION(DBaseStatusBar, Fill)
 	PARAM_FLOAT(w);
 	PARAM_FLOAT(h);
 	PARAM_INT_DEF(flags);
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	self->Fill(color, x, y, w, h);
 	return 0;
 }
diff --git a/src/v_draw.cpp b/src/v_draw.cpp
index a2caded53..a45cbddac 100644
--- a/src/v_draw.cpp
+++ b/src/v_draw.cpp
@@ -137,6 +137,8 @@ DEFINE_ACTION_FUNCTION(_Screen, DrawTexture)
 	PARAM_FLOAT(x);
 	PARAM_FLOAT(y);
 
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
+
 	FTexture *tex = animate ? TexMan(FSetTextureID(texid)) : TexMan[FSetTextureID(texid)];
 	VMVa_List args = { param + 4, 0, numparam - 4 };
 	screen->DrawTexture(tex, x, y, args);
@@ -959,6 +961,7 @@ DEFINE_ACTION_FUNCTION(_Screen, Clear)
 	PARAM_INT(y2);
 	PARAM_INT(color);
 	PARAM_INT_DEF(palcol);
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	screen->Clear(x1, y1, x2, y2, palcol, color);
 	return 0;
 }
@@ -1010,6 +1013,7 @@ DEFINE_ACTION_FUNCTION(_Screen, Dim)
 	PARAM_INT(y1);
 	PARAM_INT(w);
 	PARAM_INT(h);
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	screen->Dim(color, float(amount), x1, y1, w, h);
 	return 0;
 }
diff --git a/src/v_text.cpp b/src/v_text.cpp
index ca445913f..fa04da365 100644
--- a/src/v_text.cpp
+++ b/src/v_text.cpp
@@ -116,6 +116,7 @@ DEFINE_ACTION_FUNCTION(_Screen, DrawChar)
 	PARAM_FLOAT(y);
 	PARAM_INT(chr);
 
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	VMVa_List args = { param + 5, 0, numparam - 5 };
 	screen->DrawChar(font, cr, x, y, chr, args);
 	return 0;
@@ -241,6 +242,7 @@ DEFINE_ACTION_FUNCTION(_Screen, DrawText)
 	PARAM_FLOAT(y);
 	PARAM_STRING(chr);
 
+	if (!screen->IsLocked()) ThrowAbortException(X_OTHER, "Attempt to draw to screen outside a draw function");
 	VMVa_List args = { param + 5, 0, numparam - 5 };
 	const char *txt = chr[0] == '$' ? GStrings(&chr[1]) : chr.GetChars();
 	screen->DrawText(font, cr, x, y, txt, args);
diff --git a/src/win32/win32gliface.cpp b/src/win32/win32gliface.cpp
index b8e8cc53a..2074a17d8 100644
--- a/src/win32/win32gliface.cpp
+++ b/src/win32/win32gliface.cpp
@@ -1153,7 +1153,7 @@ void Win32GLFrameBuffer::Unlock ()
 
 bool Win32GLFrameBuffer::IsLocked () 
 { 
-	return m_Lock>0;// true;
+	return m_Lock > 0;
 }
 
 //==========================================================================
diff --git a/wadsrc/static/zscript/statusbar/heretic_sbar.txt b/wadsrc/static/zscript/statusbar/heretic_sbar.txt
index e2f761501..1273ad4ce 100644
--- a/wadsrc/static/zscript/statusbar/heretic_sbar.txt
+++ b/wadsrc/static/zscript/statusbar/heretic_sbar.txt
@@ -189,7 +189,7 @@ class HereticStatusBar : BaseStatusBar
 			y -= 40;
 		}
 
-		if (!isInventoryBarVisible() && !level.NoInventoryBar)
+		if (!isInventoryBarVisible() && !level.NoInventoryBar && CPlayer.mo.InvSel != null)
 		{
 			// This code was changed to always fit the item into the box, regardless of alignment or sprite size.
 			// Heretic's ARTIBOX is 30x30 pixels. 
diff --git a/wadsrc/static/zscript/statusbar/hexen_sbar.txt b/wadsrc/static/zscript/statusbar/hexen_sbar.txt
index 6f8318b27..f1ff81693 100644
--- a/wadsrc/static/zscript/statusbar/hexen_sbar.txt
+++ b/wadsrc/static/zscript/statusbar/hexen_sbar.txt
@@ -69,7 +69,7 @@ class HexenStatusBar : BaseStatusBar
 			DrawString(mHUDFont, FormatNumber(CPlayer.FragCount, 3), (70, -16));
 		}
 		
-		if (!isInventoryBarVisible() && !level.NoInventoryBar)
+		if (!isInventoryBarVisible() && !level.NoInventoryBar && CPlayer.mo.InvSel != null)
 		{
 			// This code was changed to always fit the item into the box, regardless of alignment or sprite size.
 			// Heretic's ARTIBOX is 30x30 pixels.