DWM's marginalizing system is incomprehensible though.
indeed. it seems that it has it's own internal margins behind it.. but they are to handle in a special range..
(the dimaond substyle of an older VS from me has completely different settings, but it took it's time to get it properly displayed)
i've thought about it and i guess the larger corners are only possible with a wider glass frame.
the corner cannot go into the inner window part (where the folderband x-axis-position begins), as seen in the preview.