3. Yet another thing (I sent this some time ago to the pdfdtex list, but because I didn't know about this list and thought that the other was the one discussing the extensions to TeX. This is the place where this message belongs to. Sorry to those who will read it twice): An intermediate scope of assignment, between \local and \global. The idea is that the assignment be still in force in the innermost group that encloses that which we are in. For example, if the primitive is to be named \regional,
...
for a long time we've been thinking of a feature like that, where results can be carried over one (or more groups); it has a low priority but it's definitely on the agenda (has even been prototyped by taco a couple of years ago)
The implementation is a bit complicated because of the way tex stores values on the save stack, which is why I never passed the prototype stage. But I still like this idea, and \regional is a good name. I will get back at this in the not-too-distant future, I hope.
4. Just one more. The todo list includes "A way to (re?)calculate the width of a \vbox, taking only the natural width of the included items into account". What about the depth of a \hbox where items have been raised? Try
\setbox0\hbox{\raise 10pt\hbox{a}}. \showthe\dp0
Yes, that problem is very similar. Best wishes, Taco