gconftool-2 --get /desktop/gnome/shell/windows/edge_tiling
To change it simply type:gconftool-2 --type=boolean --set /desktop/gnome/shell/windows/edge_tiling false
Then press, Alt-F2 and type "r" to restart gnome-shell.Unfortunately, the battle with gnome-shell isn't over.
UPDATE: ...And so the struggle continues. More stupid default behaviour in gnome-shell -- dialog boxes are locked to the titlebar. This is especially annoying when you have a large dialog box and need to enter data that is shown under it and can't move the damn dialog box. Luckily it can be changed by this command:
gconftool-2 --type=boolean --set /desktop/gnome/shell/windows/attach_modal_dialogs false