Index: code/graphics/2d.cpp
===================================================================
--- code/graphics/2d.cpp	(revision 10947)
+++ code/graphics/2d.cpp	(working copy)
@@ -151,21 +151,23 @@
 
 	gr_screen.custom_size = (w != max_w || h != max_h);
 
-	gr_screen.max_w_unscaled = w;
-	gr_screen.max_h_unscaled = h;
+	if (gr_screen.rendering_to_texture == -1) {
+		gr_screen.max_w_unscaled = w;
+		gr_screen.max_h_unscaled = h;
 
-	if (do_zoom) {
-		gr_screen.max_w_unscaled_zoomed = gr_screen.max_w_unscaled + fl2i(Gr_menu_offset_X * 2.0f / Gr_resize_X);
-		gr_screen.max_h_unscaled_zoomed = gr_screen.max_h_unscaled + fl2i(Gr_menu_offset_Y * 2.0f / Gr_resize_Y);
-		if (gr_screen.max_w_unscaled_zoomed > gr_screen.max_w_unscaled) {
+		if (do_zoom) {
+			gr_screen.max_w_unscaled_zoomed = gr_screen.max_w_unscaled + fl2i(Gr_menu_offset_X * 2.0f / Gr_resize_X);
+			gr_screen.max_h_unscaled_zoomed = gr_screen.max_h_unscaled + fl2i(Gr_menu_offset_Y * 2.0f / Gr_resize_Y);
+			if (gr_screen.max_w_unscaled_zoomed > gr_screen.max_w_unscaled) {
+				gr_screen.max_w_unscaled_zoomed = gr_screen.max_w_unscaled;
+			}
+			if (gr_screen.max_h_unscaled_zoomed > gr_screen.max_h_unscaled) {
+				gr_screen.max_h_unscaled_zoomed = gr_screen.max_h_unscaled;
+			}
+		} else {
 			gr_screen.max_w_unscaled_zoomed = gr_screen.max_w_unscaled;
-		}
-		if (gr_screen.max_h_unscaled_zoomed > gr_screen.max_h_unscaled) {
 			gr_screen.max_h_unscaled_zoomed = gr_screen.max_h_unscaled;
 		}
-	} else {
-		gr_screen.max_w_unscaled_zoomed = gr_screen.max_w_unscaled;
-		gr_screen.max_h_unscaled_zoomed = gr_screen.max_h_unscaled;
 	}
 }
 
@@ -185,8 +187,10 @@
 
 	gr_screen.custom_size = Save_custom_screen_size;
 
-	gr_screen.max_w_unscaled = gr_screen.max_w_unscaled_zoomed = (gr_screen.res == GR_1024) ? 1024 : 640;
-	gr_screen.max_h_unscaled = gr_screen.max_h_unscaled_zoomed = (gr_screen.res == GR_1024) ?  768 : 480;
+	if (gr_screen.rendering_to_texture == -1) {
+		gr_screen.max_w_unscaled = gr_screen.max_w_unscaled_zoomed = (gr_screen.res == GR_1024) ? 1024 : 640;
+		gr_screen.max_h_unscaled = gr_screen.max_h_unscaled_zoomed = (gr_screen.res == GR_1024) ?  768 : 480;
+	}
 }
 
 /**
Index: code/graphics/gropengl.cpp
===================================================================
--- code/graphics/gropengl.cpp	(revision 10947)
+++ code/graphics/gropengl.cpp	(working copy)
@@ -384,6 +384,10 @@
 	int max_w = ((to_resize) ? gr_screen.max_w_unscaled : gr_screen.max_w);
 	int max_h = ((to_resize) ? gr_screen.max_h_unscaled : gr_screen.max_h);
 
+	if ((gr_screen.rendering_to_texture != -1) && to_resize) {
+		gr_unsize_screen_pos(&max_w, &max_h);
+	}
+
 	if (x >= max_w) {
 		x = max_w - 1;
 	}