[Groff] design problem of grops

[Werner LEMBERG]

Dear friends,


while reimplementing color support in grops I stumbled over the
following problem:

Currently, this

  \Z'\m[blue]T'\M[magenta]\D'P 1c 0 -1c -1c'

and that

  \Z'\M[magenta]\D'P 1c 0 -1c -1c''\m[blue]T

produce the same, i.e., the letter `T' is visible!  I think it is not
a good idea, especially with colors.

A practical situation which exhibits this problem is striked-out text
with a colour.  With the current grops, this looks really funny.

For example, if you change the former to

  \Z'\m[blue]Test'\M[magenta]\D'P 1c 0 -1c -1c'

only `st' is visible. This is clearly a bug.

Reason for this strange behaviour is that strings are flushed out only
if something manipulates the string drawing parameter, e.g. a
different foreground color or a change of the current horizontal
position.

I will change this so that everything is output in grops as it
appears in the troff intermediate output file.  IMHO it is not the
job of grops to modify the order of how graphical operations are
applied.

A positive side effect of this change is that color handling is much
simplified.


    Werner