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Alt arrow keys print extra characters #3101

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paulwhiting opened this issue Oct 7, 2019 · 9 comments · Fixed by #3117
Closed

Alt arrow keys print extra characters #3101

paulwhiting opened this issue Oct 7, 2019 · 9 comments · Fixed by #3117
Labels
Area-Input Related to input processing (key presses, mouse, etc.) Area-TerminalControl Issues pertaining to the terminal control (input, selection, keybindings, mouse interaction, etc.) Issue-Bug It either shouldn't be doing this or needs an investigation. Needs-Tag-Fix Doesn't match tag requirements Product-Terminal The new Windows Terminal. Resolution-Fix-Committed Fix is checked in, but it might be 3-4 weeks until a release.
Milestone
Terminal-1911

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@paulwhiting
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Terminal Version: 0.5.2762.0
Microsoft Windows [Version 10.0.18362.356]

Steps to reproduce

Open terminal. Press alt-up, alt-down, alt-right, alt-left.

(For byobu: start byobu with 'byobu'. Press F2 to add a new tab. Press alt-right and alt-left to switch between tabs.)

Expected behavior

Observed behavior

  • c:\windows\system32\bash.exe: ABCD is printed out as expected.
  • c:\windows\system32\bash.exe in byobu: Byobu tabs are switched on alt-left and alt-right. (Only a single session is running so alt-up and alt-down just error out as expected.) No additional characters are printed out, as expected.
  • Windows Powershell terminal (run->powershell): Nothing is printed out. (Expected? I don't know.)
  • Terminal App powershell: ☻♠♦ is printed out.
  • Terminal App ubuntu: A◘B☻C♠D♦ is printed out.
  • Terminal App ubuntu in byobu: Byobu tabs are are switched as expected, BUT when alt is released one of ◘☻♠♦ is printed out depending on which arrow key was pressed last.
@ghost ghost added Needs-Triage It's a new issue that the core contributor team needs to triage at the next triage meeting Needs-Tag-Fix Doesn't match tag requirements labels Oct 7, 2019
@rideron89
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rideron89 commented Oct 7, 2019 •
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I'm having the same issue. Happens in both fish and bash.

I use alt-left and alt-right to navigate through words on a command.

Terminal version: 0.5.2762.0
Windows 10 version 18362.388 (1903)

@DHowett-MSFT
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Confirmed! Possible regression from #2836 (/cc @lhecker)?

@DHowett-MSFT DHowett-MSFT added Area-Input Related to input processing (key presses, mouse, etc.) Area-TerminalControl Issues pertaining to the terminal control (input, selection, keybindings, mouse interaction, etc.) Issue-Bug It either shouldn't be doing this or needs an investigation. Product-Terminal The new Windows Terminal. labels Oct 7, 2019
@ghost ghost removed the Needs-Tag-Fix Doesn't match tag requirements label Oct 7, 2019
@DHowett-MSFT DHowett-MSFT added Needs-Tag-Fix Doesn't match tag requirements and removed Needs-Triage It's a new issue that the core contributor team needs to triage at the next triage meeting labels Oct 7, 2019
@ghost ghost removed the Needs-Tag-Fix Doesn't match tag requirements label Oct 7, 2019
@DHowett-MSFT DHowett-MSFT added this to the Terminal-1910 milestone Oct 7, 2019
@lhecker
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lhecker commented Oct 8, 2019

@DHowett-MSFT This issue is caused by the use of ToUnicodeEx(), which has the following warning...

As ToUnicodeEx translates the virtual-key code, it also changes the state of the kernel-mode keyboard buffer. This state-change affects dead keys, ligatures, alt+numpad key entry, and so on. It might also cause undesired side-effects if used in conjunction with TranslateMessage (which also changes the state of the kernel-mode keyboard buffer).

I'll open a PR.

@paulwhiting I was not able to exactly replicate your observed behavior. Is there a way to switch between "keypad mode" on/off? I'm "Press[ing] alt-up, alt-down, alt-right, alt-left" (in that order) and I'm not really certain why I'm getting these different results:

  • C:\Windows\System32\bash.exe: Alt+Up/Down causes a beep (or "bing") and Alt+Left/Right jumps between words
  • Terminal App powershell: ◘☻♠♦ is printed out.
  • Terminal App ubuntu: ♦◘☻♠ is printed out.

@lhecker lhecker mentioned this issue Oct 8, 2019
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@ghost ghost added the In-PR This issue has a related PR label Oct 8, 2019
@paulwhiting
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paulwhiting commented Oct 9, 2019 •
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I believe num lock should do what you want? My keyboard doesn't have a numeric keypad, just standalone arrow keys. You're not seeing the ABCD characters because your underlying shell is handling those. It's the extra one of ♦◘☻♠ that pops up after letting go of alt that's the problem.

@DHowett-MSFT DHowett-MSFT mentioned this issue Oct 14, 2019
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@david50407
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david50407 commented Oct 15, 2019 •
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In my case, the extra keystroke will happens when I "release the Alt key" after pressing Alt+Left/Right/Up/Down.
If I don't release Alt key, the control key \cA \cB \cC \cD won't come out.

@sivaramn
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can confirm, I too face this. Within tmux, if i switch panes using Alt+direction keys, i get funny chars on the command line

@zadjii-msft zadjii-msft mentioned this issue Oct 25, 2019
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@daveshih01
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Hi folks, sorry for stating the obvious. Please review/approve the PR so this can be addressed. Thanks!

@ghost ghost added Needs-Tag-Fix Doesn't match tag requirements Resolution-Fix-Committed Fix is checked in, but it might be 3-4 weeks until a release. and removed In-PR This issue has a related PR labels Nov 13, 2019
zadjii-msft pushed a commit that referenced this issue Nov 13, 2019
@lhecker @zadjii-msft
Fixed #3101: Alt+Arrow-Keys print extra characters (#3117)
c9f148c 
## Summary of the Pull Request

This PR potentially fixes #3101.

## PR Checklist
* [x] Closes #3101.
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Requires documentation to be updated
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

## Detailed Description of the Pull Request / Additional comments

This PR fixes #3101 by setting flag 0 in `ToUnicodeEx()` even though the documentation says "If bit 0 is set, a menu is active.". I'm not 100% sure why it works, but it definitely does in this case.
I thought that bit 2, which claims that "keyboard state is not changed" would be sufficient to prevent this from happening, but it seems that's not the case.

I believe this PR should be verified by a developer at Microsoft who's familiar with the internal workings of `ToUnicodeEx()`.
We need this function (or something similar) to translate Alt+Key combinations to proper unicode.
But at the same time it should not send us any additional IBM-style Alt Codes to our character handler if that translation fails (and `ToUnicodeEx()` returns 0).

## Validation Steps Performed

See #3101 for more information. I ensured that Alt+Arrow-Key combinations do not print ◘☻♠♦ anymore.
@daveshih01
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Thanks, everyone!

@ghost
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ghost commented Nov 26, 2019

🎉This issue was addressed in #3117, which has now been successfully released as Windows Terminal Preview v0.7.3291.0.:tada:

Handy links:

@paulwhiting paulwhiting mentioned this issue Nov 27, 2019
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@j4james j4james mentioned this issue Dec 31, 2023
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Area-Input Related to input processing (key presses, mouse, etc.) Area-TerminalControl Issues pertaining to the terminal control (input, selection, keybindings, mouse interaction, etc.) Issue-Bug It either shouldn't be doing this or needs an investigation. Needs-Tag-Fix Doesn't match tag requirements Product-Terminal The new Windows Terminal. Resolution-Fix-Committed Fix is checked in, but it might be 3-4 weeks until a release.
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Fixed #3101: Alt+Arrow-Keys print extra characters
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@david50407 @sivaramn @rideron89 @paulwhiting @lhecker @DHowett-MSFT @daveshih01 @cinnamon-msft