Empty lines go up/down on debug console

[FMorschel]

Does this issue occur when all extensions are disabled?: NA

• VS Code Version: 1.97.2
• OS Version: Windows_NT x64 10.0.22631

Coming from Dart-Code/Dart-Code#5428.

Steps to Reproduce:

1. Open a Dart test file
2. Run it multiple times
3. Randomly (we've not yet identified the cause) you'll see lines getting swapped.

This is the Debug Adapter traffic:

[11:05:14] [DAP] [Info] <== {"seq":45,"type":"event","body":{"category":"stdout","output":"00:02 \u001b[32m+13\u001b[0m: ConvertToSingleQuotedStringTest | test_one_simple_unterminated_empty\u001b[0m\r\n"},"event":"output"}
[11:05:14] [DAP] [Info] <== {"seq":46,"type":"event","body":{"category":"stdout","output":"\r\n"},"event":"output"}
[11:05:14] [DAP] [Info] <== {"seq":47,"type":"event","body":{"category":"stdout","output":"00:02 \u001b[32m+14\u001b[0m: ConvertToSingleQuotedStringTest | test_raw_multiLine_threeQuotes\u001b[0m\r\n"},"event":"output"}
[11:05:14] [DAP] [Info] <== {"seq":48,"type":"event","body":{"category":"stdout","output":"\r\n"},"event":"output"}
[11:05:14] [DAP] [Info] <== {"seq":49,"type":"event","body":{"category":"stdout","output":"00:02 \u001b[32m+15\u001b[0m: ConvertToSingleQuotedStringTest | test_raw_multiLine_twoQuotes\u001b[0m\r\n"},"event":"output"}
[11:05:14] [DAP] [Info] <== {"seq":50,"type":"event","body":{"category":"stdout","output":"\r\n"},"event":"output"}

This is the output from this run:

This is a normal output:

---

CC @DanTup

[FMorschel]

At Dart-Code/Dart-Code#5428 I also mentioned:

With failing tests, this is worse because I've seen some lines getting drawn one above the other (as soon as I see it again, I can send a screenshot), and it "fixes" while hovering that line.

@DanTup answered about the empty lines:

I'm less sure that's a rendering issue, because I suspect if you scroll, the newlines will stay consistently in the places shown in the screenshot.

I've just seen it happen. Unfortunately, I have no screen recording. When I started running the tests, I saw one new line out of place but that was moved out of the screen by other tests. Now when I scrolled back, that line is back to normal. It really seems to be a rendering issue.

[FMorschel]

At about 17 seconds, the debugger is fully connected and starts running the tests.

At 19 seconds, you can see the lines going up/down. But at the end of the video, I scroll back up and it is all fine.

20250303_224304.mp4