Filebrowser: Filename collision detection

Actually in Filebrowser (e.g. by Save as...) the text-edit-field of the filename turns red if there is allready a file with the same name. My proposal is to update this valuable information while typing the filename so you can easily check out whether your filename is free for use within your saving location by character ! Second hot idea: simply use the same funktionality as above but turning green if Filebrowser is in a "File Open..." context to indicate a filename match (If you prefer typing not selecting). I don't think we need a mockup or screenshot, do we? ;)