Need to trigger a layouting to get the right panel size after we
show / hode context related items.

Change-Id: I791921ecb491bb65c53a4fe9562207d47f66a88a
Reviewed-on: https://gerrit.libreoffice.org/44565Reviewed-by: Tamás Zolnai <tamas.zolnai@collabora.com>
Tested-by: Tamás Zolnai <tamas.zolnai@collabora.com>