Transparency in fr55

hey guys whats up? facing hard times here trying to draw a bufferd canvas over the main dc without overlapping regions which used to be transparent.
i wonder if transparency is working normally in this model.

EDIT: just realized the same occurs on other models (tested on f7x). 

So, the problem here is that when i try to clear a buffered bitmap with transparent ink, the previous content will remain.


How do you guys crystal clear a bufferedbitmap so that it gets really translucent?