Hi
I would like to each application could change the client-side decorations ( like GtkHeaderBar ), like it can be made by user, but I know that this may interfere with the window grouping function, so I have an idea to combine the Window List applet and function grouping of windows.

New applet could be called: "windows group list".
By default, there would be one group: "Ungrouped windows".
This applet should have a switch button ( for e.g. arrow) to the list of groups ( like in a combobox widget ) and a list of the default or last-selected group.
After selecting a group, applet would display a list of windows of that group ( like applet "window list" ) and the switch button.
Such applet could replace: applet "window list" and the function of grouping windows in tabs.

I also thought of something else in addition to this topic.
It would be great if applications can affect the decorations drawn by KWin.
I wrote here about:
* Ordering the widgets
* Enable / disable / hide the widgets
* Change the size of window edges
* Customize window shades
* Replace window label with selected widget
( like Oxygen decoration options - of course only for all Qt or KDE applications )
Of course in decoration options user could override the application settings for the window decoration.

Note: I am not writing here about the function of grouping and sorting windows in the window list applet settings.
Is it possible and what do you think about it ?

P.S.
Sorry for my English