Switch to side-by-side view

--- a/src/qtgui/rclmain_w.h
+++ b/src/qtgui/rclmain_w.h
@@ -97,6 +97,7 @@
     virtual void startPreview(Rcl::Doc doc);
     virtual void startNativeViewer(int docnum);
     virtual void startNativeViewer(Rcl::Doc doc);
+    virtual void saveDocToFile(int docnum);
     virtual void previewNextInTab(Preview *, int sid, int docnum);
     virtual void previewPrevInTab(Preview *, int sid, int docnum);
     virtual void previewExposed(Preview *, int sid, int docnum);