Hi RandomCoder,
I am just before finishing a small todo-tree application so I came up this question some time ago. As I was not able to select individual images for each node, I added a small character to the beginning of the node text, indicating that this node has additional information.
It looks something like this (see attachment). Maybe you use this as an indication for read/unread messages.
specci48
@Erel: You can add this missing feature to the wishlist for future updates...
