yes i've done that, other skins use
<texturemask>imagename.png</texturemask>
if i remove that line from their code as youd expect the mask is lost and the thumbs become square
Adding the same line to the same xml file in streamedmp doesnt give the same result.
I've also tried <image mask> <thumbs mask> and pretty much every other type of mask ive seen used in other files of streamedmp and onther skins with no luck.
I am giving up this time, spent too much time on this the last few days with little results.