A generic control has no other functionality than displaying an optional icon centered in the control. This control type is intended
to work as a generic basis for custom control setups. See windowcontrol for generic properties of window controls and
widgetcontainer for information on widgets.
Set the bitmap rendered in the control. The bitmap will be drawn centered on the control. If the control's size is smaller
than the size of the bitmap in any dimension, the bitmap will be scaled so that it fits in the control.
Parameters
bitmap (string)
The name of the bitmap resource used as the icon
