support overwrite-mode

Change-Id: I6133aedbebd3ca358e2b916469873c38fc7453cb
Reviewed-on: https://gerrit.libreoffice.org/69761
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

vcl/source/control/edit.cxx

@@ -195,6 +195,10 @@ bool Edit::set_property(const OString &rKey, const OUString &rValue)
     {
         SetReadOnly(!toBool(rValue));
     }
+    else if (rKey == "overwrite-mode")
+    {
+        SetInsertMode(!toBool(rValue));
+    }
     else if (rKey == "visibility")
     {
         mbPassword = false;