Increase Defer timeout slack

In my experience, sometimes the selection was not being updated in time. By increasing the slack, we should catch the selection change more frequently.

src/ui.js

@@ -2547,7 +2547,7 @@ class Toolbar {
                                         flash(input);
                                     }
                                 }
-                            }, 4);
+                            }, 8);
                         }
                     }
                 }