Respect current search string when toggling advanced button

This fixes a bug in the properties panel in which the advanced
button state changed slot would not respect the current search
string and thus show all properties.

Change-Id: Iea6dc6061a7914a127256f4ebe725bb4a57dad4f
Merge topic '13990-fix-panel-search' into next

0a49447 Respect current search string when toggling advanced button