---

5 Information in widget structure

• integer ID for identifying the widget to the C server
• widget class keyword (e.g. :FORM, :PUSH-BUTTON-GADGET, :UNKNOWN)
• parent widget
• list of (known) children
• USER-DATA slot for programmer use
• list of active callback lists
• list of active protocol lists
• list of active event handlers

The last three are for internal use in cleaning up Lisp state on widget destruction