Opening the Merge BibTeX dialog on multi-monitor setup

[stefan-kolb]

When running JabRef in a multi-monitor setup, e.g. on the second screen, the merge BibTeX dialog always appears on the first screen and not on the screen where the current JabRef instance is running on.

Also applies to other dialogs!

[stefan-kolb]

See http://stackoverflow.com/questions/4627553/show-jframe-in-a-specific-screen-in-dual-monitor-configuration

[stefan-kolb]

Reason is inside PositionWindow.java where the saved location of non modal windows is always adapted to be inside the bounds of the first monitor, to not allow settings outside the screen.