title: Overwritting Cut / Copy / Paste to wx.TextCtrl
body: <p>So I'm learning wxPython and to do so I'm working on a text editor.  I know that I can intercept a CUT / COPY / PASTE signal generated from a control, such as wx.TextCtrl by binding the equivalent wx.EVT_TEXT_COPY / wx.EVT_TEXT_PASTE / wx.EVT_TEXT_CUT.  What I'm having trouble figuring out is how to override say a paste to the clipboard with other text.</p>
  
  <p>For instance I have a wx.ListBox where a user can store clips of text and then select them latter to paste onto the wx.TextCtrl instead of whatever text is on the system clipboard.  So basically I'm trying to intercept the paste signal and in lieu of pasting the system clipboard text have it paste the selected line from the wx.ListBox.  Is this possible?  If so, how would I go about doing this? </p>