CellRendererIcon: add active state - SL #3989
CellRendererIcon: add active state - SL #3989

For press feedback.  Do this connecting to the treeview press and
release signals, as the palette invoker does.  After this, the active
state can be styled in the artwork.

Signed-off-by: Manuel Quiñones <6f5069c5b6be23302a13accec56587944be09079@laptop.org>
Acked-by: Simon Schampijer <088e16a1019277b15d58faf0541e11910eb756f6@laptop.org>
Signed-off-by: Ajay Garg <1c58a446a63e719d7b90156a8998ccc461609ed7@activitycentral.com>

ceibal-tatu/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit-gtk3