X-atomic-property-set-if-unset! -- Set property NAME on WINDOW to VALUE, if it's currently unset.
Synopsis
(X-atomic-property-set-if-unset! window name value #&optional
(type "STRING") (format 8))
Description
Set property NAME on WINDOW to VALUE, if it's currently unset.
Returns #f if the property is already set, #t otherwise.
TYPE and FORMAT are as in X-property-set!