diff --git a/window.c b/window.c
--- a/window.c
+++ b/window.c
@@ -1020,7 +1020,9 @@ void MouseLoop()
 		if (_game_mode == GM_MENU)
 			return;
 
-		if (mousewheel && !(w->flags4 & WF_DISABLE_VP_SCROLL)) {
+		// only allow zooming in-out in main window, or in viewports
+		if ( mousewheel && !(w->flags4 & WF_DISABLE_VP_SCROLL) && 
+			   (w->window_class == WC_MAIN_WINDOW || w->window_class == WC_EXTRA_VIEW_PORT) ) {
 			ZoomInOrOutToCursorWindow(mousewheel < 0,w);
 		}