A generalized boolean.
output-pane-cache-display caches the display of the output-pane
, that is what it currently shows. The result can be used later by output-pane-draw-from-cached-display.
When from-display-p is false the cached display is created by a "dummy" call to the display-callback of output-pane . If from-display-p is true the cached display is created by copying whatever is currently showing on the screen. Note that any obscured part of the pane will not be copied in this case. The default value of from-display-p is false.
Before caching the display,
output-pane-cache-display performs an implicit call to output-pane-free-cached-display, which undoes the effect of all previous Cached Display interface calls.
CAPI User Guide and Reference Manual (Macintosh version) - 3 Aug 2017