fixed in case "force" is used and Preferences storage is selected.
fixed in case "force" is used and Preferences storage is selected.

use case:
user checks "show on startup"
  preference is set to FALSE
developer forces tip dialog
checkbox is not check, user checks "show on startup"
  as only FALSE was persisted by the code, the preference is not changed
  -> now it will remove the preference thus tip dialog will be shown

Issue 357

RockManJoe64/swingx,RockManJoe64/swingx