Fix requery behaviour of MemoryCursor.

As we can't restore the contents of the cursor window, we need to keep
it on deactivation so we can restore it on requery().

Change-Id: I06f688bbe9120c307bdc3ddbc3833416becdec82
Merge "Fix requery behaviour of MemoryCursor." into cm-10.1
Merge branch 'cm-10.1' into martincz