http://bugs.winehq.org/show_bug.cgi?id=20270
--- Comment #12 from unimatrix andrejx@gmail.com 2009-10-06 09:59:55 --- (In reply to comment #11)
Confirming. Currently the dialog is sizable only if the OFN_ENABLESIZING flag is provided (Winamp does not). MSDN says that the flag is only needed if a hook procedure or custom template is provided (Winamp does not). Preliminary test confirms this.
Then what is the 3rd option? Obviously it has to exist since Windows makes it resizable.