This brings back global menu support in KWin.
The DBusMenu infrastructure is different that we just read the DBus service name and
menu object path from the windows rather than passing around window IDs on DBus which
won't work on Wayland.
Differential Revision: https://phabricator.kde.org/D3089
The decoration button configuration interface is merged into the QML
part using two list views (left buttons, right buttons) and a grid
view for all the available buttons.
* Border Sizes
* Close menu double click
Both are added to the Settings and exposed in the decoration kcm.
As it started to no longer scale the kcm uses a ui file.
Still missing:
* buttons
* custom decoration configuration
* GHNS
* search
Following features are supported:
* finds all plugins
** finds all themes for a theme-engine plugin
* renders previews for the plugin/themes
* loads currently used plugin/theme
* saves selected plugin/theme
* triggers config reload in KWin
Following features are currently not supported:
* Search
* Plugin configuration
* GHNS
* Button configuration
