tdf#101536 sw: do load Insert Index dialog's document ReadOnly

Turns out SwOneExampleFrame is used for different things, so load doc
read-only only if it's an existing document.

(regression from 6a8407d8)

Change-Id: I0a1ab0725ed9dccca23742c9d83cd9635a188edf

sw/source/uibase/utlui/unotools.cxx

@@ -137,12 +137,14 @@ void SwOneExampleFrame::CreateControl()
             sTempURL = sArgumentURL;
         aURL <<= sTempURL;
 
-        uno::Sequence<beans::PropertyValue> aSeq(2);
+        uno::Sequence<beans::PropertyValue> aSeq(3);
         beans::PropertyValue* pValues = aSeq.getArray();
         pValues[0].Name = "OpenFlags";
         pValues[0].Value <<= OUString("-RB");
         pValues[1].Name = "Referer";
         pValues[1].Value <<= OUString("private:user");
+        pValues[2].Name = "ReadOnly";
+        pValues[2].Value <<= (sTempURL != cFactory);
         uno::Any aArgs(aSeq);
 
         xPrSet->setPropertyValue( "LoaderArguments", aArgs );