You'll need to actually use writepixelfast or writepixel to write the transparent alpha information to the black areas i'm afraid... i wrote some functions to write this stuff..
http://www.blitzbasic.com/codearcs/codearcs.php?code=1013
:o) Hope that helps
http://www.blitzbasic.com/codearcs/codearcs.php?code=1013
:o) Hope that helps