Don't remember for sure, but the problem may have existed since B1 (but I'm pretty sure it doesn't exist in SE2013).
The "Files" diaglog has two columns, "Name" and "Path". The width of the "Name" column used to auto-adjust to the longest file name among the files shown in the dialog. It doesn't do that in Beta of SE 2014, and it appears that it just uses the width used the last time the dialog was shown.
I've noticed this on Linux and Windows (both 64-bit).
Is this a new behavior introduced in SE 2014?