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6afa955a2e
Thanks to Jiri Kaspar for sending this patch (apart from the new docs
section, which is in my own words), which implements a feature we've
had as a wishlist item ('utf8-plus-vt100') for a long time.
I was actually surprised it was possible to implement it in so few
lines of code! I'd forgotten, or possibly never noticed in the first
place, that even in UTF-8 mode PuTTY not only accepts but still
_processes_ all the ISO 2022 control sequences and shift characters,
and keeps running track of all the same state in term->cset and
term->cset_attrs that it tracks in IS0-2022-enabled modes. It's just
that in UTF-8 mode, at the very last minute when a character+attribute
pair is about to be written into the terminal's character buffer, it
deliberately ignores the contents of those variables.
So all that was needed was a new flag checked at that last moment
which causes it not quite to ignore them after all, and bingo,
utf8-plus-vt100 is supported. And it works no matter which ISO 2022
sequences you're using; whether you're using ESC ( 0 to select the
line drawing set directly into GL and ESC ( B to get back when you're
done, or whether you send a preliminary ESC ( B ESC ) 0 to get GL/GR
to be ASCII and line drawing respectively so you can use SI and SO as
one-byte mode switches thereafter, both work just as well.
This implementation strategy has a couple of consequences, which I
don't think matter very much one way or the other but I document them
just in case they turn out to be important later:
- if an application expecting this mode has already filled your
terminal window with lqqqqqqqqk, then enabling this mode in Change
Settings won't retroactively turn them into the line drawing
characters you wanted, because no memory is preserved in the screen
buffer of what the ISO 2022 state was when they were printed. So
the application still has to do a screen refresh.
- on the other hand, if you already sent the ESC ( 0 or whatever to
put the terminal _into_ line drawing mode, and then you turn on
this mode in Change Settings, you _will_ still be in line drawing
mode, because the system _does_ remember your current ISO 2022
state at all times, whether it's currently applying it to output
printing characters or not.
PuTTY README
============
This is the README file for the PuTTY installer distribution. If
you're reading this, you've probably just run our installer and
installed PuTTY on your system.
What should I do next?
----------------------
If you want to use PuTTY to connect to other computers, or use PSFTP
to transfer files, you should just be able to run them from the
Start menu.
If you want to use the command-line-only file transfer utility PSCP,
you will probably want to put the PuTTY installation directory on
your PATH. On Windows 7 and similar versions, you can do this at
Control Panel > System and Security > System > Advanced system
settings > Environment Variables.
Some versions of Windows will refuse to run HTML Help files (.CHM)
if they are installed on a network drive. If you have installed
PuTTY on a network drive, you might want to check that the help file
works properly. If not, see http://support.microsoft.com/kb/896054
for information on how to solve this problem.
What do I do if it doesn't work?
--------------------------------
The PuTTY home web site is
https://www.chiark.greenend.org.uk/~sgtatham/putty/
Here you will find our list of known bugs and pending feature
requests. If your problem is not listed in there, or in the FAQ, or
in the manuals, read the Feedback page to find out how to report
bugs to us. PLEASE read the Feedback page carefully: it is there to
save you time as well as us. Do not send us one-line bug reports
telling us `it doesn't work'.