Terminal: WinEvents and ConPTY question

Created on 4 Jul 2019 · 4Comments · Source: microsoft/terminal

A few days ago I noticed that NeoVim in tmux does not pick up resize events properly, but mysteriously when a different console window is resized, it suddenly fixes itself. I just tracked this down to the fact that libuv is listening for the EVENT_CONSOLE_LAYOUT WinEvent for any window, which doesn't seem to be firing for PTY layout changes.

Now, I believe this is a libuv bug and they should be handling WINDOW_BUFFER_SIZE_EVENT. But before ConPTY existed, their way did work.

Basically I'm looking for some clarification here - what are the console WinEvents supposed to be for, and should they be enabled for PTYs as well? And if not, it might be a good idea to document that they are only sent for actual conhost windows.

Area-Interop Issue-Question Product-Conpty Resolution-Answered

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parkovski

Most helpful comment

Hey, it's really funny that you should mention this. I'm working on filing a bug on them for this exact issue, because their winevent hook degrades performance for _all console workloads_ by a few percentage points if a libuv thing is running whatsoever.

I believe that _WinEvents are not part of the compatibility guarantee for pseudoconsoles._ @miniksa can keep me honest here.

DHowett-MSFT on 4 Jul 2019

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All 4 comments

I believe that _WinEvents are not part of the compatibility guarantee for pseudoconsoles._ @miniksa can keep me honest here.

DHowett-MSFT on 4 Jul 2019

👍2

More info: https://github.com/microsoft/terminal/issues/410 @parkovski

oising on 4 Jul 2019

👍1

Hey, it's really funny that you should mention this. I'm working on filing a bug on them for this exact issue, because their winevent hook degrades performance for _all console workloads_ by a few percentage points if a libuv thing is running whatsoever.

I believe that _WinEvents are not part of the compatibility guarantee for pseudoconsoles._ @miniksa can keep me honest here.

Correct. Given that UIA (released 2005) is the replacement for WinEvents/MSAA (released 1997) and UIA is significantly less terrible than MSAA performance-wise (and otherwise), we didn't consider it during the implementation of ConPTY (2018).

Also, MSAA and UIA are for accessibility tools and user interface testing. I don't guarantee anything if you're not attempting to use them for those purposes.