Bring back the remembering feature of the expanded/collapsed status of the tools. See issue 2648. Additionnally, correct a GUI bug of the B&W tool: the display wasn't initialized correctly when opening a new editor.

rtgui/filepanel.h

@@ -82,6 +82,7 @@ class FilePanel : public Gtk::HPaned,
 
         void setParent (RTWindow* p) { parent = p; }
         void init (); // dont call it directly, the constructor calls it as idle source
+        void on_realize ();
         void setAspect();
         void open (const Glib::ustring& d); // open a file or a directory
         void refreshEditedState (const std::set<Glib::ustring>& efiles) { fileCatalog->refreshEditedState (efiles); }