Support Server-Side Decoration (SSD) layout
Would it be possible to do the same of Drawing app (link) i.e. detect if the current DE/WM uses Server Side Decoration, disable Client Side Decoration (CSD), and make the header bar look and feel like a toolbar?
This is how Drawing looks on KDE Plasma/KWin that uses SSD Instead of CSD (while it's still possible to drag the window from the headerbar/toolbar the right click menu on it is disabled):