def s(item, action)
      {
        //   vvv Error: needed writable value, got [event 'System.Windows.Forms.ToolStripItem.Click']
        item.Click += fun(_, _) { action() } 
      }
      
      s(openToolStripButton, openFile);
      
      openToolStripButton.Click += fun(_, _) { openFile() } // ok