I created a 6-tile .bmp image and saved it as the corner fill button. I created an advanced button using the corner fill button image. I set the alignment and visibility as per the copy of the button code below. I did not have a visibility option of 'add to frame' (SKS5) so I set it to always show & show if window rolled up (just in case).
I couldn't get the button to show when rolled up until I changed the button order & made it Button0 - I applied the skin after saving it & the button painted the corner perfectly. However, the magic pink pixels in the Titlebar were showing then (as often happens when making repeated changes to a skin & applying it multiple times), so I deleted the skin temp files (.wb4, ~*.*, etc.) and when I reapplied the skin, the button no longer showed up. I haven't been able to get it to reappear since.
Is 'attach to frame' just in SKS6?
