#i122221# fix slide selected in Slide Pane with Page Up

The comment in the removed part says to call SelectPage to make 
the slide visible. But the following NotifyCurrentSlideChange method 
calls SelectPage for the page makes it visible if the pane is not updated yet.

git-svn-id: https://svn.apache.org/repos/asf/openoffice/trunk@1559671 13f79535-47bb-0310-9956-ffa450edef68