Switch to side-by-side view

--- a/src/sampleconf/mimeview
+++ b/src/sampleconf/mimeview
@@ -54,6 +54,7 @@
 application/x-chm = kchmviewer %f
 application/x-fsdirectory = dolphin %f
 application/x-gnuinfo = xterm -e "info -f %f"
+application/x-gnumeric = gnumeric %f
 
 application/x-flac = rhythmbox %f
 audio/mpeg = rhythmbox %f