Fix palette damage for tool buttons, fixes #4960
Fix palette damage for tool buttons, fixes #4960

Currently, the ToolInvoker code passes the button child in such a
way that the WidgetInvoker queues only the child's draw.  In previous
Gtk+ versions, this magically resulted in redrawing the parent as well.

However, Gtk+ 3.20 is probably trying to save power and not randomly
redraw widgets.  To fix this, we must queue the redraw of the widget
that we want to redraw explicitly.

quozl/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3