tdf#91592 WRITER crashes when navigating through comments

without rSh.EnterStdMode, the image is selected and it has no GetTextNode.

Change-Id: I91ed5a1ed002a04919042f4df22c49d3189daccd
Reviewed-on: https://gerrit.libreoffice.org/15952Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit 4826007f)
Reviewed-on: https://gerrit.libreoffice.org/16031

sw/source/uibase/uiview/viewmdi.cxx

@@ -423,6 +423,7 @@ IMPL_LINK( SwView, MoveNavigationHdl, bool *, pbNext )
 
         case NID_POSTIT:
             {
+                rSh.EnterStdMode();
                 sw::sidebarwindows::SwSidebarWin* pPostIt = GetPostItMgr()->GetActiveSidebarWin();
                 if (pPostIt)
                     GetPostItMgr()->SetActiveSidebarWin(0);