bug#3356: 23.0.93; Loss of undo info in calc

[Jay Belanger]

Leo <sdl.web@gmail.com> writes:
...
> 1. M-x calc
> 2. do some calculation for example: ' sqrt ( x ) RET a t x 5 RET
> 3. type q to quit calc
> 4. M-x calc to bring it back
> 5. type U
>
> You will get "No further undo information is available".

calc-quit sets the undo list to nil on purpose, probably to save limited
memory in the early days.   If there are still memory considerations,
then calc-quit could truncate the undo list rather than remove it,
otherwise it'd be easy to have calc-quit not do anything with the undo
list.

> Incidentally, I wonder whether making the two windows dedicated is more
> desirable than current behaviour.

Maybe, but I wonder if this would cause problems in some situations.
How would full-calc be affected, for instance.

Jay