Created attachment 136130 [details] A window with no maximize button displayed properly in Breeze binary decoration Attached is a window without a maximize button (Strawberry album art) being displayed correctly in the binary Breeze theme.
Created attachment 136131 [details] A focused window with no maximize button displayed incorrectly in Kite aurorae decoration Here is the same window displayed with the Kite Aurorae theme -- when the window is focused the maximize button is still displayed.
Created attachment 136132 [details] An unfocused window with no maximize button displayed incorrectly in Kite aurorae decoration Here is the same window with the Kite Aurorae decoration when the window is unfocused. Notice the ugly big gap left by the disappearing maximize button.
Created attachment 136134 [details] Breeze binary decoration displaying window correctly without close button ... and it doesn't only happen for the maximize button. Here is a window displayed correctly without a close button. ...
Created attachment 136135 [details] A focused window with no close button displayed incorrectly in Kite aurorae decoration ... here is the same window intentionally with no close button (download new global themes) displayed incorrectly in the Kite Aurorae decoration. Confusingly you will try to click the close button and nothing will happen.
Created attachment 136136 [details] An unfocused window with no close button displayed incorrectly in Kite aurorae decoration Here is what happens when the window intentionally without a close button is unfocused in Aurorae.
Created attachment 136137 [details] A focused window with no close button displayed incorrectly in Kite aurorae decoration Attached the wrong image for a focused window with no close button displayed incorrectly in Kite aurorae decoration in comment 4. This is the correct version of what was attachment 136135 [details].
I realised that this is because I did not specify a deactivated button design in my svgs for the "Kite" aurorae decoration (as described at https://techbase.kde.org/User:Mgraesslin/Aurorae). Aurorae decorations such as "Spectrum" specify such and display a greyed out button. However, I'd prefer a behaviour consistent with the Breeze binary behaviour where no button is displayed at all if the button is disabled.
Preferred design: If you specify a deactivated style in your svg, display it. If you don't specify a deactivated style in your svg then do not display a button at all (and no gaps). The current fallback behaviour when no deactivated style is specified in your svg is still not adequate because of the inconsistency between an active and inactive window, and is confusing because the user may try to click what looks like a button that should work.
Yeah, it's a good idea not to display disabled buttons if the decoration theme doesn't provide a style for them.