add support for additional _NET_WM_WINDOW_TYPEs

- add support for _NET_WM_WINDOW_TYPE_COMBO
- add support for _NET_WM_WINDOW_TYPE_DND
- add support for _NET_WM_WINDOW_TYPE_DROPDOWN_MENU
- add support for _NET_WM_WINDOW_TYPE_POPUP_MENU
- add support for _NET_WM_WINDOW_TYPE_TOOLTIP