How to add Freemarker to text properties?

I would like to override the title of the "Top Category Experts" widget to include the name of the current Category/Board.  I figured I could just embed Freemarker into the text property value, but this does not work.  I just get the literal Freemarker text.  Can someone tell me how I can add dynamic data such as the Category or Board name to this widget's title?  Thanks.