Sets or removes the stipple bitmap. The stipple is only used when the brush's style is wx:const-stipple or wx:const-opaque-stipple (see also set-style), , but setting the bitmap to null turns off the stipple bitmap. A bitmap cannot be used as a stipple if it is selected into a wx:memory-dc% object.
A brush cannot be modified if it was obtained from a wx:brush-list% or while it is selected into a drawing context.
Under X Windows, the stipple is a mask between the wx:bitmap object and current colour. Under Windows, the current colour is ignored, and the bitmap colour is used.