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

Backspacing offscreen should not be possible #191

New Issue
Closed
opened 2026-01-30 21:45:10 +00:00 by claunia · 5 comments
claunia commented 2026-01-30 21:45:10 +00:00
Owner
Copy Link

Originally created by @j4james on GitHub (Mar 14, 2018).

Originally assigned to: @zadjii-msft on GitHub.

  • Your Windows build number:

Microsoft Windows [Version 10.0.16299.248]

  • What you're doing and what's happening:

If I output a sequence of backspace characters when the cursor position is in the leftmost column of the screen, I would expect that to have no effect, since the cursor can't move any further leftward. And this is the behaviour that I see in DOS, the old Windows console, and the Linux console. On the new Windows 10 console, though, a backspace in the leftmost column causes the cursor position to wrap around to the end of the previous line.

For example, enter the following command in a bash console:

printf "\b\b\b\bTEST\n"

On Linux that outputs "TEST" at the start of the line, while in the Windows 10 console it outputs "TEST" at the end of the previous line.

What is really odd, though, is if the cursor is positioned in the top left corner of the screen, a backspace command can actually end up moving the cursor entirely offscreen.

For this to occur, you need to have something in the scrollback buffer, so you'll first have to do a directory listing or something that fills up the screen. Then enter the following command:

printf "\033[H\033[J\b\b\b\bTEST\n"

Note that the "TEST" is not visible onscreen, but if you scroll up, you'll see that it has been output at the end of the line above the top of the screen.

  • What's wrong / what should be happening instead:

I don't think a backspace should have any effect when the cursor is in the leftmost column of the screen. But even if that backspace wrapping is intentional, I definitely wouldn't expect it to apply when the cursor is in the top left corner of the screen.

Originally created by @j4james on GitHub (Mar 14, 2018). Originally assigned to: @zadjii-msft on GitHub. * Your Windows build number: Microsoft Windows [Version 10.0.16299.248] * What you're doing and what's happening: If I output a sequence of backspace characters when the cursor position is in the leftmost column of the screen, I would expect that to have no effect, since the cursor can't move any further leftward. And this is the behaviour that I see in DOS, the old Windows console, and the Linux console. On the new Windows 10 console, though, a backspace in the leftmost column causes the cursor position to wrap around to the end of the previous line. For example, enter the following command in a bash console: printf "\b\b\b\bTEST\n" On Linux that outputs "TEST" at the start of the line, while in the Windows 10 console it outputs "TEST" at the end of the previous line. What is really odd, though, is if the cursor is positioned in the top left corner of the screen, a backspace command can actually end up moving the cursor entirely offscreen. For this to occur, you need to have something in the scrollback buffer, so you'll first have to do a directory listing or something that fills up the screen. Then enter the following command: printf "\033[H\033[J\b\b\b\bTEST\n" Note that the "TEST" is not visible onscreen, but if you scroll up, you'll see that it has been output at the end of the line above the top of the screen. * What's wrong / what should be happening instead: I don't think a backspace should have any effect when the cursor is in the leftmost column of the screen. But even if that backspace wrapping is intentional, I definitely wouldn't expect it to apply when the cursor is in the top left corner of the screen.
claunia added the Product-Conhost label 2026-01-30 21:45:10 +00:00
claunia commented 2026-01-30 21:45:11 +00:00
Author
Owner
Copy Link

@zadjii-msft commented on GitHub (Mar 15, 2018):

I'll need to double check this is a regression from v1, but assuming it is, this definitely counts as a bug. Even if it's not, that's not what I'd expect to happen - we can certainly try and fix this.

@zadjii-msft commented on GitHub (Mar 15, 2018): I'll need to double check this is a regression from v1, but assuming it is, this definitely counts as a bug. Even if it's not, that's not what I'd expect to happen - we can certainly try and fix this.
claunia commented 2026-01-30 21:45:11 +00:00
Author
Owner
Copy Link

@j4james commented on GitHub (Mar 16, 2018):

Just to be clear, when I said the old Windows console I meant the console on older versions of Windows (I was testing Windows Vista to be more specific) and not the pre-AU console on Windows 10. Not sure if that aligns with your idea of v1.

Btw thank you for the fantastic work you've been doing on the console - the new functionality is much appreciated.

@j4james commented on GitHub (Mar 16, 2018): Just to be clear, when I said the old Windows console I meant the console on older versions of Windows (I was testing Windows Vista to be more specific) and not the pre-AU console on Windows 10. Not sure if that aligns with your idea of v1. Btw thank you for the fantastic work you've been doing on the console - the new functionality is much appreciated.
claunia commented 2026-01-30 21:45:11 +00:00
Author
Owner
Copy Link

@zadjii-msft commented on GitHub (Mar 16, 2018):

@j4james Yea, that's what I mean when I say v1. "Conhostv1" is a version of the console code that was parked when the console was first getting some love at the beginning of Windows 10. So, when you check the "Use legacy Console" checkbox, that's the same experience as everything before windows 10.

@zadjii-msft commented on GitHub (Mar 16, 2018): @j4james Yea, that's what I mean when I say v1. "Conhostv1" is a version of the console code that was parked when the console was first getting some love at the beginning of Windows 10. So, when you check the "Use legacy Console" checkbox, that's the same experience as everything before windows 10.
claunia commented 2026-01-30 21:45:12 +00:00
Author
Owner
Copy Link

@DHowett-MSFT commented on GitHub (Nov 21, 2018):

It looks like this fix shipped in the 1809 update. Thanks for reporting!

@DHowett-MSFT commented on GitHub (Nov 21, 2018): It looks like this fix shipped in the 1809 update. Thanks for reporting!
claunia commented 2026-01-30 21:45:12 +00:00
Author
Owner
Copy Link

@egmontkob commented on GitHub (Nov 13, 2019):

For future reference:

I don't think a backspace should have any effect when the cursor is in the leftmost column of the screen.

In xterm, this is controlled by the "Reverse-wraparound Mode": printf "\e[?45h" / printf "\e[?45l"

screen and urxvt perform reverse-wraparound, whereas tmux wraps backwards only across implicit overflows and not across explicit newlines. I don't know how many terminals support toggling the mode.

The desired behavior is potentially part of a much broader picture: to make sure entering a multi-line string in cooked tty mode is an okay user experience, even if one has to correct a typo just at the margin. See https://gitlab.gnome.org/GNOME/vte/issues/62.

But even if that backspace wrapping is intentional, I definitely wouldn't expect it to apply when the cursor is in the top left corner of the screen.

I agree, the cursor shouldn't be able to walk back to the scrollback buffer.

@egmontkob commented on GitHub (Nov 13, 2019): For future reference: > I don't think a backspace should have any effect when the cursor is in the leftmost column of the screen. In xterm, this is controlled by the "Reverse-wraparound Mode": `printf "\e[?45h"` / `printf "\e[?45l"` `screen` and `urxvt` perform reverse-wraparound, whereas `tmux` wraps backwards only across implicit overflows and not across explicit newlines. I don't know how many terminals support toggling the mode. The desired behavior is potentially part of a much broader picture: to make sure entering a multi-line string in cooked tty mode is an okay user experience, even if one has to correct a typo just at the margin. See https://gitlab.gnome.org/GNOME/vte/issues/62. > But even if that backspace wrapping is intentional, I definitely wouldn't expect it to apply when the cursor is in the top left corner of the screen. I agree, the cursor shouldn't be able to walk back to the scrollback buffer.
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 Product-Conhost
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#191
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?