Window menu
Minimize Window — Shrink the frontmost window down into the Dock.
Zoom — Switch the frontmost window between the biggest size possible and the last size you set.
Bring All to Front — Get all of the OmniFocus windows up in front of other applications’ windows.
Toggle Quick Entry Window — Show or hide the Quick Entry window; note that you can customize a keyboard shortcut for this, and use the shortcut from within any application.
At the bottom of the Window menu is a list of all of your OmniFocus windows; choose one to bring it to the front.