- The complete transparent background image for [Button.InActiveMinimizeBackgroundBlock] or [Button.InactiveMinimizeBackgroundBlockColoured] is not properly loaded. There is always some background if you move the mouse over the minimize button of an INACTIVE window. You can see this behaviour in the Midnight theme, but it seems that other themes are also affected.
I think this is actually only happening with [Button.InActiveMinimizeBackgroundBlock], and I'm thinking it might just be a typo because it's spelled "InActive" on that property while everything else is "Inactive" (although manually adjusting the casing in the code doesn't work either).
I'm not exactly sure what the "Coloured" suffix refers to, but it's apparent some programs use those button versions and some don't, as this bug can be demonstrated here:
Above, the left window is using [Button.InActiveMinimizeBackgroundBlock], and the custom image is not working.
Now here, the right window is using [Button.InactiveMinimizeBackgroundBlockColoured], and the custom image is working.
It's also maybe worth adding that the window buttons in particular have some other odd rendering quirks. I don't know if it's the image sizing (currently using 45x124, but I've tried many others) or what, but the edges of the buttons are getting distorted. If you look at the dark gap between the minimize and maximize button, for example, you'll see it's 2px wide:
It doesn't look like much, but it's actually supposed to only be 1px, and is getting stretched when it's rendered. Compare with the original file that the buttons are sliced from:
So, I'm guessing there's a reason the default themes are relying only on glyphs at the moment.