You'll need the developer tools installed to do this. Do a Show Package Contents on Hydra itself (control-click on the application and select that option from the pop-up menu), then navigate to Contents -> Resources -> English.lproj, and double-click on TextDocument.nib, at which point a bunch of windows will fly open.
Grab the TextDocument.nib window, select the Instances tab, and double-click on Window. Resize and move the resulting window to wherever you like, then resize the large blue box it contains to the same shape and size. Quit Project Builder; it will ask you to save, and make sure you select Documents Format when you save. And you're done.

