I already talked about the inability of choosing more than one Control in the list to move at once (if you have 20 Controls, 10 TextFields and 10 Labels, you have to move, say, 10 Controls to set all TextFields together in your own correct order).
Now I will talk about the size of the window: it resize to its default if you reopen it - in the same session -.
And… the better for the end:
you do not have the complete list of controls; as an example, I miss two BevelButtons (2 are displayed, 2 are not displayed in the Tab Order Window).
Worst, I have a complete set of Controls that are not displayed too (they are related to the same feature: the ID Photo for the Record person in a db “personnal” project).
This comes from a George Harrison (old) song: “Isn’t It a Pity ?”
The other thing worth pointing out is that there is an “auto adjust tab order” option, next to the shoe tab order, which is able to arrange tab order horizontally, then vertically or vice versa. Often solves the problem without any effort.