Changes:
- added invalidate call after entry selection and expand

Behaviour before patch (Linux):
1. Open Writer
2. Open AutoText Dialog: Tools > AutoText
3. Expand/select entry

Insert button is still disabled / entry is not expanded.
To force repaint you had to use mouse scroll.

Change-Id: I814db71dea02273998f675c3b140d554f2e109ba
Reviewed-on: https://gerrit.libreoffice.org/25783Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>