A wxGraphicsBrush is a native representation of a brush. The contents are specific and private to the respective renderer. Instances are ref counted and can therefore be assigned as usual. The only way to get a valid instance is via wxGraphicsContext:createBrush/2 or wxGraphicsRenderer:createBrush/2.
This class is derived (and can use functions) from: wxGraphicsObject
wxWidgets docs: wxGraphicsBrush
wxGraphicsBrush() = wx:wx_object()