From Xojo Documentation
The initial locations at which the window could open.
|Default||The default placement based upon the OS. Often this is Staggered.|
|ParentWindow||Over the parent window if it opens another window.|
|MainScreen||On the primary or main screen on a multi-screen setup.|
|ParentWindowScreen||On the same screen as the parent window in a multi-screen setup.|
|Staggered||New windows open slightly offset to the top and left from previously opened windows.|