Connection starts normally. But if I switch to other tab (eg Far Manager) and back to PuTTY tab, now it's totally gray (sometimes I can see a couple of lines in the bottom). Below this gray rectangle PuTTY is still working: I can type exit+Enter and tab closes. I can even run mc.
I'm not sure where is the bug - in ConEmu, in PuTTY or in Windows itself.
When running PuTTY standalone it works fine over local proxy. But there is no tab to switch away and back! ;-)
I tested different SSH servers - gray rectangle appears everywhere.
I used simple port forwarder instead of plink - nothing changes.
What shall I do to reproduce the problem on my local PC?
You need SSH server with public key auth (and working public key).
Run PuTTY (in new console), enter Host Name, go to Connection / SSH / Proxy, set Proxy type to Local, Telnet command to plink root@%host -nc localhost:22 (Sample PuTTY session is included in zip below).
Activate another tab and PuTTY tab back.
After gray rectangle appears, press CtrlWinAltSpace. PuTTY window must appears. How it will be?
This console is fully functional. No gray rectangles.
It seems CtrlWinAltSpace is quick-n-dirty workaround for this bug :-)