Change Col-width in Openxchange Dialog

[kockiren]

I use Open-Xchange in Version 6.20.6 Rev3 and when i write a new Mail and choose an attachment from the Infostore i get a dialog, but if the Filename is long i can't see the whole name of the file and i cant change the width of this column. Anybody knows how to change the col-width of this dialog?

THX
Rene