fdo#76953: cannot start show at selected slide

It was worked only in slide sorter view properly.
It seems it leads undefined behaviour when a menu item
is in the menubar.xml but has no definition in *.sdi file.
I experienced that on windows menu item was disabled
on linux it was enabled.

Change-Id: Iba4dd1cbac60a3b3350604d64d60d10d050a4e2b