Resizing the 'Save As' window in Windows 7

The window is maximized. You can unmaximize it using the keyboard shortcut Windows+Down Arrow or by double-clicking the title bar. (That there is no unmaximize button and the resizer doesn't work can certainly be considered a bug.)

This works for Windows 8 - it may help you on other windows versions. Click Alt-spacebar. you should get the little action box in the upper left of the screen. Click on Restore. This should re-size the save as window, and allow you to use the mouse to drag the screen size to your desired size.

Good luck.

Double-click the window's top bar.

Got this tip from pcreview.co.uk forums:

Question: When saving emails from Outlook, the Save As dialog box goes full screen, and I can't get it to resize smaller to normal dialog box size. […] There seems to be no option to minimize or maximize.

Answer: Double click on the title bar to restore it.