In TortoiseHg Workbench, when you commit and have added files, a dialog appears:
Confirm Add Add selected untracked files? [Add] [Cancel] [Show Details...]
I think that it would be a small improvement to remove the "Show Details..." button and simply automatically display the list of details. I don't know whether the dialog is auto-sized to the length of that list, but it need not be.. if the list is long, a scrollable list showing 10 lines or so would be fine.
Workbench has a pretty complex UI, and I think that this would be a way to simplify one small part of it with no negative side effects.