I have an application that has LSUIElement = 1 in the Info.plist. When I run the application, a dock item and toplevel menu bar is created for it. Why?
EDIT:
I was using a library that was calling TransformProcessType(), clobbering my Info.plist configuration.
Go to your Info.plist file, and add a new key-value pair, or type Boolean. Start typing in the key the phrase "Application is agent". It should auto-complete for you. Then check the checkbox.
This is how I create my agent applications, and it works every time!