microsoft / microsoft/terminal

DEC double-height lines do not properly reset

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Area-Output Area-VT Issue-Bug Priority-3 Product-Terminal
Dominant language
C++
Stars
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Forks
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Avg merge
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Merged PRs (30d)
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Description

### Windows Terminal version

1.17.11461.0

### Windows build number

10.0.19045.3086

### Other Software

_No response_

### Steps to reproduce

Create DEC double-height text via an echo command. (It can be tricky to echo the escape character.)

Clear screen, do a directory.

Watch as double-height line artifacts that shouldn't be there are there.
Not just once. Multiple double-height lines can keep reoccurring.

* Even issuing the ANSI reset ("0m") code fails to remove the artifacting behavior.
* Even clearing the screen multiple times fails to remove the artifacting behavior.

![image](https://github.com/microsoft/terminal/assets/789591/8ce91c37-56cc-430d-af45-be520e17691a)

![image](https://github.com/microsoft/terminal/assets/789591/a450818b-0fa8-426f-9f05-1a0fb84d6a14)
![image](https://github.com/microsoft/terminal/assets/789591/5feeefab-3100-42c5-abf8-849cbea918e3)

### Expected Behavior

The expected behavior is one the line is finished rendering, no double-height letters would ever appear again except if another line is issued with the escape code to turn that double-height letters on.

### Actual Behavior

The actual behavior is that after the line is finished rendering, double-height letters still keep appearing -- often many many many times -- even without another line issued with the escape code to turn double-height letters on.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the issue in Windows Terminal 1.17.11461.0 on Windows 10.0.19045.3086 using DEC double-height text, then clear the screen and run a directory listing. Done means double-height artifacts do not recur after the line finishes, ANSI reset, or repeated screen clears unless a later escape sequence enables them.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
cli, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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