The function simple-pane-handle can be used to retrieve the "handle" of a displayed pane. Similarly current-dialog-handle returns the handle of the current dialog, if there is one.
The handle is the representation in the underlying GUI system, and may be useful in some situations for performing operations for which there is no CAPI interface.
CAPI User Guide and Reference Manual (Macintosh version) - 01 Dec 2021 19:31:25