don't let stale pointers around.
don't let stale pointers around.

This fixes the bug when one adds a mixer, it becomes the default, then
removes it and use one of the global volume modifiers, it would use
the stale pointer.

TODO: a way to configure the volume independently of a shelf gadget.



git-svn-id: 6ac5796aeae0cef97fb47bcc287d4ce899c6fa6e@48593 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33

jordemort/e17,jordemort/e17,jordemort/e17