remove dropfeedback when showing overlay

src/vs/workbench/browser/parts/editor/sideBySideEditorControl.ts

@@ -1001,6 +1001,10 @@ export class SideBySideEditorControl implements ISideBySideEditorControl, IVerti
 					destroyOverlay(); // somehow we managed to move the mouse quickly out of the current overlay, so destroy it
 				}
 				createOverlay(target);
+
+				if (overlay) {
+					DOM.removeClass(node, 'dropfeedback'); // if we show an overlay, we can remove the drop feedback from the editor background
+				}
 			}
 		}));