title: catch mouse press event on Notebook without touching tabs and their contents
body: <p>I'm programming in <em>gtkD</em> on <em>Funtoo Linux</em>.<br/>
  I want to catch mouse press event in <em>Notebook</em>,<br/>
  but I would like to don't touch the tabs and their contents.<br/>
  I'm using function: <em>addOnButtonPress ()</em> in <em>Notebook</em>,<br/>
  but after that the tabs aren't reorderable ( <strong>previously yes</strong> ).<br/>
  Or similarly, how to catch mouse events only on the selected window / widget without touching it's children.<br/>
  Thanks for any help.</p>