After some reading, definitely, for sure, the BMP file format supports an alpha channel, although some call it transparency, and alphas and layer transparency technically aren't the same thing.

I couldn't get a 32-bit splash screen to load when I had transparency saved.

It can be done. I'm not sure, though, that Xara is set up to recognize alpha information in a BMP image. I've been through several esoteric programs that claim they will save a BMP with transparency, but either the channel order is wrong, or it can't be done by mortals.

This is a screen snag of Painter loading in front of part of my Desktop. The lettering has an alpha around it, showing the patterned page I have behind it in Xara.

Click image for larger version.  Name: painter-loading.jpg  Views: 229  Size: 173.6 KB  ID: 97166


Technically, it's do-able.

By us? probably not!