ToggleToolbutton: do hide the tooltip when clicked or touched

This is the same behaviour as for the RadioToolButton and the
ToolButton. See 5a1b380dd6 where
we did the same for the RadioToolbutton.

Updated the toolbuttons.py test to be able to test that code
path.

Signed-off-by: Simon Schampijer <simon@laptop.org>
Acked-by: Manuel Quiñones <manuq@laptop.org>

src/sugar3/graphics/toggletoolbutton.py

@@ -141,4 +141,8 @@ class ToggleToolButton(Gtk.ToggleToolButton):
 
         return False
 
+    def do_clicked(self):
+        if self.palette:
+            self.palette.popdown(True)
+
     palette = property(get_palette, set_palette)

tests/graphics/toolbuttons.py

@@ -37,6 +37,7 @@ toolbar_box.toolbar.insert(color_button, -1)
 color_button.show()
 
 favorite_button = ToggleToolButton('emblem-favorite')
+favorite_button.set_tooltip('Favorite')
 toolbar_box.toolbar.insert(favorite_button, -1)
 favorite_button.show()