#1 Closing application windows should not quit apps

[Len Sassaman]

[OS X 10.3.9, otrproxy 0.2.0...]

Closing the otrproxy window terminates the otrproxy application.
Under OS X, this is unexpected behavior. Closing the window should
simply close the window, not end the running application.

Suggestion:

1. Add a "File --> Show Connections" menu item.
2. No longer quit otrproxy when the connections window is closed.
3. Allow the connections window to be redisplayed by selecting the
"File --> Show Connections" item. (hotkey suggestion: Command-N).