Yes you can. Inherit your class from the treecontrol and add a new property
for Selections. Maintain an arraylist in your class for selected nodes. then
every time the user clicks on a node, depending on the Ctrl or Shift button
status, add the nodes into the arraylist. Expose this arraylist as
Selections from your tree control.
As far as the drawing of selected items is concerned, you will need to
override OnBeforeSelect and OnAfterSelect and do your painting work
Hope this helps,
--Saurabh