In this section:
These three call-back functions transfer information between the edit box (%eb (Edit Box), %rd (Edit Integer), %rf (Edit Floating Point), %fs (Directory for File Dialog), or %re (Multiline Edit Box)) that has the focus and the clipboard. Typically, they are used as the call-back function for an edit-copy/cut/paste menu item. These call-back functions require no additional winio@ arguments.
Menu items and buttons attached to these callback functions are greyed according to circumstances. For example, a control associated with the CUT function would be greyed if no text were currently marked as selected on the screen. However, if the control has a grey control variable then this variable takes precedence.
Apart from %eb, standard accelerator keys (Ctrl+C, Ctrl+X, and Ctrl+V) can also be used for COPY, CUT and PASTE.