Comment 2 for bug 1402441

If I set GTK_DEBUG=1, the (first, as it occurs only once per run) click of the "start" indicator menu option outputs:

Gtk-Message: /usr/share/themes/Lubuntu-default/gtk-2.0/gtkrc:45: failed to retrieve property `GtkRange::activate-slider' of type `gboolean' from rc file value "((GString*) 0x7f41969caf20)" of type `GString'

Checking out /usr/share/themes/Lubuntu-default/gtk-2.0/gtkrc shows that this is probably not a serious issue, probably caused by an outdated rc file:

[...]
18: style "default" {
[...]
45: GtkScrollbar ::activate-slider = FALSE
[...]

So this message is probably not connected.