Taking this task: https://phabricator.wikimedia.org/T46529 as an example, we see that the tree is displayed in a way that it is impossible to see which actual tasks are displayed - only "T7..." is displayed and even hover, usually displaying the task label, does not work there.
I think it would be better if it displayed the full task ID and title, even at the expense of enabling the scroll in the box (which is there anyway for a wide enough tree) or maybe displayed just the ID and enabled the hover display?