- On platforms supporting it (the X11 based platforms), selects the
- so called PRIMARY SELECTION as the clipboard as opposed to the
- normal clipboard, if primary is True.
+ On platforms supporting it (the X11 based platforms), selects the so
+ called PRIMARY SELECTION as the clipboard as opposed to the normal
+ clipboard, if primary is True. On other platforms all clipboard
+ operations fail when using the primary selection. This allows code
+ supporting the primary selection to be written without ill effects on
+ the other platforms.