Since this is related to the use of KDE with Wayland (I don't recall this problem with the X session), I'm leaving it here just in case someone else is bugged by this:
To better match GTK decoration buttons with KDE ones when using CSD (client side decoration), like Firefox or Thunderbird do with titlebar hidden, there is the need to install devel/dconf:
It still doesn't draw the red circle to the close button (if you configured it), but at least is a better match.
To better match GTK decoration buttons with KDE ones when using CSD (client side decoration), like Firefox or Thunderbird do with titlebar hidden, there is the need to install devel/dconf:
It still doesn't draw the red circle to the close button (if you configured it), but at least is a better match.