@Joomla_Direct Yes, Captions is compatible with Joomla 1.5. A new version will also be released this week.
20 January 2012
JCE 2.0.20 released
This is a maintenance update to fix a few bugs and improve Joomla! 2.5 compatability.
Due to a change in the way the editor is now loaded, this release should resolve issues with Virtuemart 1.1.9 and any extension that loaded the editor in a tab - redShop, JEvents, etc.
For a full list of changes and bugs fixed see the Changelog