Proposal for a new internal panel-plugin : a "fake" handle

[Nick Schermer]

Well I have some issues with it (sorry for the late response):

1) After changing the style, it seems to be impossible to get the
right-click menu (probably a destroyed widget without setting
xfce_panel_plugin_menu_show_configure again).
2) What exactly does "expanding empty space" do? Because it pushes
other plugin off my panel and I can hardly believe this is on purpose.
3) You can't expand with a line anymore (duno how trivial that is),
but maybe 4 styles and an expand option is better?
4) Lots of code duplication.

I can fix all those issues myself, but I'd like to have some more info
on points 2 and 3 before I start hacking on it ^_^.

Cheers,
Nick