title: gtk logic behind treeviewcolumns needing cell renderers
body: <p>From what I understand about GTK, if I have a TreeView, I can't just use any widget I want to display information about a column. For text, you need a <code>gtk.CellRendererText</code>. For toggle buttons, a <code>gtk.CellRendererToggle</code>. For anything else, it seems you have to implement yourself, which, from a sample one for buttons that I saw, doesn't look straightforward.</p>
  
  <p>Firstly, is this the case? Is there an easy way to set up whatever widget you want to be used to display some text? If not, then why is it implemented this way? If I were designing GTK i would just create some sort of system where when a row was added and when some data model information changes, user-specified callbacks would be called which would add the appropriate widget or change it, respectively.</p>