Eo: fix double callback deletion
- Same signal/function/data registered twice on e.g mouse_down
- On mouse_down, register mouse_move and mouse_up
- On mouse_up, unregister mouse_move
Result: mouse_move still invoked after mouse_up
- When the mouse_move callback deletion is required, the cb is
flagged as deleted but is not freed as walking_list blocks.
- When the second (and same) has to be deleted, it will try to delete
the first again because the delete_me flag is not checked.
This patch fixes it by checking the delete_me flag when determining the