[galaxy-dev] optional=true for param type=float

Hi I want a float parameter which is optional, so the field displayed to the user is blank, and validated as float if user enters a value, i try this: <param name="abc" type="float" optional="True" value="" label="a number" /> but get the "A real number is required" error. Looking in the code, "class FloatToolParameter( TextToolParameter )" in http://bitbucket.org/galaxy/galaxy-central/src/tip/lib/galaxy/tools/paramete... it seems like the optional parameter handling is missing. Cheers M