Handle cell activation by button-release

src/sugar/graphics/icon.py

@@ -1033,10 +1033,12 @@ class CellRendererIcon(gtk.GenericCellRenderer):
 
         return xoffset, yoffset, width, height
 
-    def on_activate(self, event, widget, path, background_area, cell_area, flags):
-        self.emit('activate', path)
+    def on_activate(self, event, widget, path, background_area, cell_area,
+                    flags):
+        pass
 
-    def on_start_editing(self, event, widget, path, background_area, cell_area, flags):
+    def on_start_editing(self, event, widget, path, background_area, cell_area,
+                         flags):
         pass
 
     def _is_prelit(self, tree_view):

src/sugar/graphics/palette.py

@@ -1230,6 +1230,13 @@ class CellRendererInvoker(Invoker):
         self.notify_mouse_leave()
 
     def __button_release_event_cb(self, widget, event):
+        if event.button == 1 and self._point_in_cell_renderer(event.x, event.y):
+            tree_view = self._tree_view
+            path, column_, x_, y_ = tree_view.get_path_at_pos(int(event.x),
+                                                              int(event.y))
+            self._cell_renderer.emit('activate', path)
+            # So the treeview receives it and knows a drag isn't going on
+            return False
         if event.button == 3 and self._point_in_cell_renderer(event.x, event.y):
             self.notify_right_click()
             return True