Exactly, but this makes it impossible to blit a bmap with transparency onto another bmap that is using transparency aswell - which is what I'm trying to do.

The only workaround I can come up with is using bmap_process. This way I could specify the blending mode in the shader's pass myself.
However, in that case the whole bmap needs to be processed for every single bmap that I want to blit which is a bit of an overkill for blitting a lot of small bmaps into a big one.

I could temporarily try to use this workaround but I hope that there'll be a way to alter how draw_-functions blend their content into the target-bmap, or simply chaging these functions to always use "correct" blending.