I filed a bug due to the app not behaving properly under native window manager because of the borderless design, but the bug was swiftly moved to the bug-graveyard (App not obeying system's window manager (KDE)).
I find it a rather poor ux design that giving back a considerable amount of control over the app window behaviour in the context of modern multi-window, -desktop and -screen environments is considered regressive and secondary to having an in-vogue themeability of the window border.