starred/terminal
1
0
Fork 0
mirror of https://github.com/microsoft/terminal.git synced 2026-02-04 05:35:20 +00:00
Code Issues 19.0k Packages Projects Releases 20 Wiki Activity

More cursor droppings #11326

New Issue
Closed
opened 2026-01-31 02:44:37 +00:00 by claunia · 2 comments
claunia commented 2026-01-31 02:44:37 +00:00
Owner
Copy Link

Originally created by @j4james on GitHub (Nov 10, 2020).

Environment

Windows build number: Version 10.0.18362.1082
Windows Terminal version (if applicable): commit 64aa911aee

Steps to reproduce

  1. Build a recent version of OpenConsole.
  2. Using that build, open a bash shell in conhost.
  3. Open the console properties and go to the Layout section.
  4. Uncheck the Wrap text output on resize option.
  5. Set the Screen Buffer Width to 100 and the Window Width to 80.
  6. Save these settings and then execute the following command in the bash shell:
printf "\e[2 q\e[2J\e[1;82H"; sleep 1; printf "\e[5B \b"; sleep 5

What this sequence is doing:

  1. Set the cursor to a non-blinking block so it's easier to see.
  2. Clear the screen.
  3. Move the cursor position to column 82 which forces the viewport to scroll right.
  4. Sleep for a second so the cursor becomes visible at that position.
  5. Move the cursor down a few lines.
  6. Output a space and backspace to force the cursor to redraw.
  7. Sleep a few seconds so you can see the results.

Expected behavior

When the cursor moves down, it should be erased from line 1, and then redrawn on line 5.

Actual behavior

When the cursor moves down, it isn't erased from line 1, so you end up with two copies of the cursor.

image

What's happening is that when the cursor is moved, the SetConsoleCursorPositionImpl method adjusts the viewport to make sure the new position will be visible onscreen. Before that happens, though, there's a call to SCREEN_INFORMATION::MoveToBottom which forces the viewport X coordinate to zero. So at the time of the actual move calculation, it briefly appears as if the cursor is offscreen, and thus not visible, so the code doesn't trigger a repaint.

So in step 5 of the test case, when the cursor moves down, there's no repaint to hide the old position, and also actually no repaint to render the new position. It's only the output in step 6 that forces the cursor to repaint, but by that point it's too late to erase the old cursor position.

I think the fix for this is just to make MoveToBottom preserve the current X coordinate. This would actually improve the behaviour of the unwrapped viewport in general, so either way I think it's a good thing. However, the catch is that it's then more likely for the console to trigger the crash from issue #1976, so that needs to be fixed first (I think I have a solution for that too).

Originally created by @j4james on GitHub (Nov 10, 2020). # Environment Windows build number: Version 10.0.18362.1082 Windows Terminal version (if applicable): commit 64aa911aeeaffac0e5dcd9368176483153cf5401 # Steps to reproduce 1. Build a recent version of OpenConsole. 2. Using that build, open a bash shell in conhost. 3. Open the console properties and go to the _Layout_ section. 4. Uncheck the _Wrap text output on resize_ option. 5. Set the Screen Buffer Width to 100 and the Window Width to 80. 6. Save these settings and then execute the following command in the bash shell: ```` printf "\e[2 q\e[2J\e[1;82H"; sleep 1; printf "\e[5B \b"; sleep 5 ```` What this sequence is doing: 1. Set the cursor to a non-blinking block so it's easier to see. 2. Clear the screen. 3. Move the cursor position to column 82 which forces the viewport to scroll right. 4. Sleep for a second so the cursor becomes visible at that position. 5. Move the cursor down a few lines. 6. Output a space and backspace to force the cursor to redraw. 7. Sleep a few seconds so you can see the results. # Expected behavior When the cursor moves down, it should be erased from line 1, and then redrawn on line 5. # Actual behavior When the cursor moves down, it *isn't* erased from line 1, so you end up with two copies of the cursor. ![image](https://user-images.githubusercontent.com/4181424/98683235-b5dc2900-235c-11eb-8d15-fbad00e9c0a9.png) What's happening is that when the cursor is moved, the `SetConsoleCursorPositionImpl` method adjusts the viewport to make sure the new position will be visible onscreen. Before that happens, though, there's a call to `SCREEN_INFORMATION::MoveToBottom` which forces the viewport X coordinate to zero. So at the time of the actual move calculation, it briefly appears as if the cursor is offscreen, and thus not visible, so the code doesn't trigger a repaint. So in step 5 of the test case, when the cursor moves down, there's no repaint to hide the old position, and also actually no repaint to render the new position. It's only the output in step 6 that forces the cursor to repaint, but by that point it's too late to erase the old cursor position. I think the fix for this is just to make `MoveToBottom` preserve the current X coordinate. This would actually improve the behaviour of the unwrapped viewport in general, so either way I think it's a good thing. However, the catch is that it's then more likely for the console to trigger the crash from issue #1976, so that needs to be fixed first (I think I have a solution for that too).
claunia commented 2026-01-31 02:44:39 +00:00
Author
Owner
Copy Link

@zadjii-msft commented on GitHub (Nov 12, 2020):

Oh gosh, welcome to the cursor turds rabbit hole 😄. Thanks for the investigation and the write up - best of luck to any who dare venture forth into madness

@zadjii-msft commented on GitHub (Nov 12, 2020): Oh gosh, welcome to the cursor turds rabbit hole 😄. Thanks for the investigation and the write up - best of luck to any who dare venture forth into madness
claunia commented 2026-01-31 02:44:39 +00:00
Author
Owner
Copy Link

@ghost commented on GitHub (Jan 28, 2021):

:tada:This issue was addressed in #8434, which has now been successfully released as Windows Terminal Preview v1.6.10272.0.🎉

Handy links:

@ghost commented on GitHub (Jan 28, 2021): :tada:This issue was addressed in #8434, which has now been successfully released as `Windows Terminal Preview v1.6.10272.0`.:tada: Handy links: * [Release Notes](https://github.com/microsoft/terminal/releases/tag/v1.6.10272.0) * [Store Download](https://www.microsoft.com/store/apps/9n8g5rfz9xk3?cid=storebadge&ocid=badge)
Sign in to join this conversation.
No Branch/Tag Specified
Branches Tags
Labels
Clear labels
⛺ Reserved
A11yCO
A11yMAS
A11ySev1
A11ySev2
A11ySev3
A11yTTValidated
A11yUsable
A11yVoiceAccess
A11yWCAG
Area-Accessibility
Area-AtlasEngine
Area-AzureShell
Area-Build
Area-Build
Area-Chat
Area-CmdPal
Area-CodeHealth
Area-Commandline
Area-CookedRead
Area-DefApp
Area-Extensibility
Area-Fonts
Area-GroupPolicy
Area-i18n
Area-Input
Area-Interaction
Area-Interop
Area-Localization
Area-Output
Area-Performance
Area-Portable
Area-Quality
Area-Remoting
Area-Rendering
Area-Schema
Area-Server
Area-Settings
Area-SettingsUI
Area-ShellExtension
Area-ShellExtension
Area-ShellExtension
Area-Suggestions
Area-Suggestions
Area-TerminalConnection
Area-TerminalControl
Area-Theming
Area-UserInterface
Area-VT
Area-Windowing
Area-WPFControl
AutoMerge
Blocking-Ingestion
Culprit-Centennial
Culprit-WinUI
Disability-All
Disability-Blind
Disability-LowVision
Disability-Mobility
External-Blocked-WinUI3
Fixed
Gathering-Data
good first issue
HCL-E+D
HCL-WindowsTerminal
Help Wanted
Impact-Compatibility
Impact-Compliance
Impact-Correctness
Impact-Visual
In-PR
InclusionBacklog
InclusionBacklog-Windows TerminalWin32
InclusionCommitted-202206
Issue-Bug
Issue-Docs
Issue-Feature
Issue-Feature
Issue-Question
Issue-Samples
Issue-Scenario
Issue-Task
Needs-Attention
Needs-Author-Feedback
Needs-Bisect
Needs-Discussion
Needs-Repro
Needs-Tag-Fix
Needs-Tag-Fix
Needs-Triage
No-Recent-Activity
Priority-0
Priority-1
Priority-2
Priority-3
Product-Cmd.exe
Product-Colortool
Product-Colortool
Product-Colortool
Product-Conhost
Product-Conpty
Product-Meta
Product-Powershell
Product-Terminal
Product-WSL
pull-request
Mirrored from GitHub Pull Request
 Resolution-Answered
Resolution-By-Design
Resolution-Duplicate
Resolution-External
Resolution-Fix-Available
Resolution-Fix-Committed
Resolution-No-Repro
Resolution-Won't-Fix
Severity-Blocking
Severity-Crash
Severity-DataLoss
spam
this-will-be-a-breaking-change
Tracking-External
WindowsTerminal_Win32
Work-Item
zAskModeBug
zInbox-Bug
No Label Area-Rendering Issue-Bug Priority-3 Product-Conhost Resolution-Fix-Committed
Milestone
No items
No Milestone
Projects
Clear projects
No project
Assignees
Clear assignees
claunia
No Assignees
1 Participants
Notifications
Due Date
No due date set.
Dependencies

No dependencies set.

Reference: starred/terminal#11326
Delete Branch "%!s()"

Deleting a branch is permanent. Although the deleted branch may continue to exist for a short time before it actually gets removed, it CANNOT be undone in most cases. Continue?