That bug has been opened on https://launchpad.net/distros/ubuntu/+source/gtk+2.0/+bug/75324

"Today, many people use resolution like 1280*1024 and even 1600*1200.

Todays file selector dialog is WAY to small. It should use a (configurable) percent of the screen height/width.

I KNOW that this is one of the reasons people think Linux is bad. Maybe it sounds strange, but if the first thing you see is a tiny tiny file selector and you have to scroll forever you get get pretty dissapointed if you are used to the windows file selector. It is better then gnomes. Time to change that ...
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> Thank you for your bug. Could you attach a screenshot illustrating your problem? Is your problem the ~5 folder lines displayed by default?
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Yes.

It should be more like 75% of screen height and not a fixed number of lines.

I se nog god reason why not fill more of the screen as the user has made the choice to select a file. When you have 100+ files and dirs in a directory (home dir for example) and you only see ~5 lines at the time it takes to much time scrolling."