Switch to side-by-side view

--- a/dirbrowser/dirbrowser.h
+++ b/dirbrowser/dirbrowser.h
@@ -41,6 +41,7 @@
     void onCurrentTabChanged(int);
     void changeTabTitle(QWidget *, const QString&);
     void onSearchcapsChanged();
+    void onSortprefs();
 
     void openSearchPanel();
     void closeSearchPanel();