[Feature Request] Support more buttons

[renyuneyun]

KDE has a few more window (title bar) buttons. This plasmoid/widget/applet supports some but not all of them. Could it support more of them someday?

I'm aware some buttons may not make sense for this plasmoid (e.g. scroll/collapse), but some does make sense (e.g. window options). So maybe there can be a wider selective set. In particular, the following two should be useful:

• [ ] Window options This could also be done in applet-window-title.
• [ ] Appmenu button This does not fully contradict with applet-window-appmenu, because this is one button that will show a (vertical) compact list.