This is adapted from the code that I originally wrote for the
conditional format dialogs.

Change-Id: I3349b7c720d99ede595cc6ebea2046e0f9dadc57
Reviewed-on: https://gerrit.libreoffice.org/41653Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>