The problem is not the CSD itself, the problems are the CSD that don't uses GTK buttons, and the dialog windows, like DevTool that don't need the CSD. So, the developers should add an option to enable or disable the CSD, if it is enable, it should apply only for main windows but not the dialog ones, and use GTK buttons; if disable, simply do not show the button on the site of taskbar and show the titlebar on all windows.
Posts made by rexfx
RE: Opera 55. Getting rid of that ugly CSDOpera for Linux