Syntax
#(proc,%button.clicked,...)
%button specifies a button control. You can define this to be a proc which gets called when the button is clicked.
Example
Def:Button:example-panel.my-button [*]My Button[*] Def:Proc:example-panel.my-button.clicked [*] #(def,example-panel.my-button.label,I Was Clicked) [*]