title: [Qt]Customising QTreeWidgetItem
body: <p>I want to customise QTreeWidgetItem. I wish to add to it, two Toolbuttons and a string.  Also I wish to add these to only one column in the treewidget.</p>
  
  <p>I tried to subclass QTreeWidgetItem but realised I coult not "paint" on it as it is not derived from QWidget.</p>
  
  <p>I then tried using QTreeWidget::setItemWidget(QTreeWidgetItem *item, int column, QWidget widget);However, the button overlaps over the text written to the item. If I add widgets to different columns, using the above call, I'm not able to acheive the look and feel the way I want to.</p>
  
  <p>How do I acheive this?</p>
  
  <p>Also, I want to change my "+/-"(expand collapse) buttons to triangular buttons as in Vista.
  I saw an example where they do it using stylesheets, but is there another way to do it through code?</p>
  
  <p>Thanks</p>