Fix #31514: Open blends via drag-n'-drop doesn't work when splash screen is on

Do not block EVT_DROP event from popup handler.
Not ideal solution sine it'll be much nicer to cleanup event handling order,
but should be acceptable for now.

source/blender/editors/interface/interface_handlers.c

@@ -6574,7 +6574,16 @@ static int ui_handler_popup(bContext *C, wmEvent *event, void *userdata)
 	/* delayed apply callbacks */
 	ui_apply_but_funcs_after(C);
 
-	/* we block all events, this is modal interaction */
+	if (event->type == EVT_DROP) {
+		/* if we're handling drop event we'll want it to be handled by popup callee as well,
+		 * so it'll be possible to perform such operations as opening .blend files by dropping
+		 * them into blender even if there's opened popup like splash screen (sergey)
+		 */
+
+		return WM_UI_HANDLER_CONTINUE;
+	}
+
+	/* we block all events, this is modal interaction, except for drop events which is described above */
 	return WM_UI_HANDLER_BREAK;
 }