How to set up web variable screen for filtering by attributes

Hi out there,

My problem deals with the query variable selection screen in the web. I would like to filter some variables by their attributes in the same way it is done in the navigation item, but in the selection screen I have only the characteristic values in the F4 help available. Is there a way to adjust or extend the selection screen so that I can also filter by attributes (without having to modify the corresponding ABAP Class)?

By the way this functionality exists for selection screen in BEx, so why doesn't it exist in the web?

I'd appreciate any idea.

thanx,

Heiko