experiment with splitted views based on karsten's input.
The goal is to support both the emacs usecase and the usecase with fixed views for certain sets of files. The changes gives the user more control where the files are. Effectively it should be easy now to put your cpp files in the left pane, and the header files in the right pane, and use F4 to toggle between them. Also make the 'x' in the toolbar close the document, and not the view.