Switch to side-by-side view

--- a/src/qtgui/recoll.pro.in
+++ b/src/qtgui/recoll.pro.in
@@ -19,6 +19,7 @@
         crontool.h \
         editdialog.h \
         firstidx.h \
+        fragbuts.h \
         idxsched.h \
         listdialog.h \
         preview_w.h \
@@ -41,6 +42,7 @@
         confgui/confgui.cpp \
         confgui/confguiindex.cpp \
         crontool.cpp \
+        fragbuts.cpp \
         guiutils.cpp \
         main.cpp \
         multisave.cpp \