fpicker: Respect the PrepareExecute() result

Change-Id: I351eaa76da01656638de5f04eb376e5b16102b4a

fpicker/source/office/iodlg.cxx

@@ -1683,7 +1683,8 @@ short SvtFileDialog::Execute()
 
 void SvtFileDialog::StartExecuteModal( const Link<Dialog&,void>& rEndDialogHdl )
 {
-    PrepareExecute();
+    if (!PrepareExecute())
+        return;
 
     // start of the dialog
     ModalDialog::StartExecuteModal( rEndDialogHdl );