[plt-scheme] double buffering under 203

Hello everybody i have got a little prob (of course)

under 103p i was doing double buffering by swaping a dc% and a bitmap-dc%

but now when i try i am told:
203 said:"set-clipping-region in dc<%>: device context is not ok: #<struct:object:bitmap-dc%>
So
-why does the bitmap%-dc does not accept region setting?
-Am i going into the wall? {º_}}

thanx for all the fish :-)

dadoux le lispien foo 
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