On this page:
command
get-font
Version: 4.2.1

control<%> : interface?
  implements: subwindow<%>
The control<%> interface is implemented by the built-in control window classes:

(send a-control command event)  void?
  event : (is-a?/c control-event%)
Calls the control’s callback function, passing on the given control-event% object.

(send a-control get-font)  (is-a?/c font%)
Returns the font used for the control, which is optionally supplied when a control is created.