+ Label to display on the button (may be empty if only bitmap is used).}
+@row3col{bitmap, @ref overview_xrcformat_type_bitmap,
+ Bitmap to display in the button (optional).}
+@row3col{bitmapposition, @c wxLEFT|wxRIGHT|wxTOP|wxBOTTOM,
+ Position of the bitmap in the button, see wxButton::SetBitmapPosition().}