Why are my file selection dialogs so big? How do I make them smaller?

I managed to find a solution by figuring out that the dialog modal is always 1440 px wide. So I did grep -r "1440" ~/.config (I also looked in ~/.gnome, ~/.gconf, ~/.gconfd/ but they didn't turn up anything interesting.) I stumbled upon this gem:

.config/gtk-2.0/gtkfilechooser.ini:GeometryWidth=1440

Removing that line (and the corresponding GeometryHeight) solved the problem for me.

The window size in stored in a dconf key. You should install dconf-editor (it's in the software centre). Then, navigate to org.gtk.settings.file-chooser and adjust the window-size key.

Does this solve your problem?

I solved this by modifying a plugin in compiz-config manager: Windows Manager:Windows Rules:Size Rules:

New-> Size Windows: "type=Dialog", and set the size.