When I select a revision in the "History View" and then hit CMD+SHIFT+U to update to that revision, it brings up the update dialog, with the current selected revision being pre-selected. When I try to make the update happen, however, not by clicking the "Update" button, but by just hitting Return, sometimes it will perform the update, but sometimes the table goes to editing mode and I will edit the "branch" column. It depends on whether this table has focus when the dialog comes up or not. Initially, when I open MacHG, the table will always have focus and thus I'm always editing and have to hit the Update button with the mouse or hit Tab until I moved focus out of the table and the view below it.
I think when the update dialog is opened, it should always make sure focus is not on the anything but the dialog itself. Even if I moved focus to the table the last time I used the dialog, focus should not be there anymore next time I open the dialog.