It looks like the NAWS info is only being sent once, after the DO NAWS/WILL NAWS handshake. It should be getting sent each time the window is resized (or when the font size changes).
(this is with 3.32)
The code looks like it should be working. Do you have a test case where I can try it?
Connect to Cryosphere.net:6666, log in, type 'rows', note screen size, resize window in mushclient, type 'rows' again, see that it has not been updated.
Just done a packet trace and verified that nothing is getting sent apart from the first time.
Ok, I've found the problem here. I was resizing the actual window with the grab bars and expecting it to Just Work.
After experimentation, one of our users who uses mushclient reported that it's only sent when the window size is changed in Game>Configure. Apparently selecting "adjust width to window size" causes the NAWS info to be sent. (Sorry for the vagueness here, I'm relaying this info, not in windows atm).
Is there some way of making this automatic?
It should Just Work, I have that on my list of things to investigate.