I am not getting along with the mask editor (Uv/Image editor) when trying to feather. I gather you can feather a mask by shift-clicking. But if you have Fill selected the extra points seem to have no effect?
Thanks
Select the mask points and use Alt+S, then drag your mouse. See https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.64/Mask_Editor for more info
