SetViewPort

Try drawing a rectangular area of the source image instead of using viewport as apparently it's not reliable on all systems (so I've heard ...)

Here's is TonyG's code:

Function tg_drawimagerect(image:TImage,x:Int,y:Int,xs:Int,ys:Int,width:Int,height:Int)
    DrawImage LoadImage(PixmapWindow(LockImage(image),xs,ys,width,height)),x,y
End Function