Debug console scrolls near top after each evaluated line after exception raised in debug console

[bersbersbers]

Issue Type: Bug

See also microsoft/vscode-python#4725 - but note that vscode-python people say they

do not control the scrolling behavior of the debug console in VS Code

Expected behaviour

Debug console behaves normally

Actual behaviour

Debug console scrolls to top after each evaluated line

Steps to reproduce:

1. Save this code as Bug.py:

import sys
sys.exit()

2. Enable breakpoints at "Uncaught exceptions"
3. Debug Bug.py in VS Code
4. When hitting SystemExit exception, run print(1) in Debug console.
5. Run sys.exit() a bunch of times (1-5 times) in the Debug console.
6. Notice that at one point, Debug console scrolls to top
7. Scroll to bottom of Debug console output
8. Run print(2) in Debug console.
9. Notice that you don't see 2 due to Debug console scrolling near top again.

VS Code version: Code 1.32.1 (05f146c, 2019-03-08T00:51:49.278Z)
OS version: Windows_NT x64 10.0.17763

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-4310M CPU @ 2.70GHz (4 x 2694)
GPU Status	2d_canvas: enabled checker_imaging: disabled_off flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software rasterization: unavailable_off surface_synchronization: enabled_on video_decode: enabled webgl: enabled webgl2: unavailable_off
Memory (System)	7.91GB (2.69GB free)
Process Argv
Screen Reader	no
VM	0%

Extensions (5)

Extension	Author (truncated)	Version
latex-workshop	Jam	6.2.0
svn-scm	joh	1.47.1
python	ms-	2019.2.5558
multi-command	ryu	1.3.0
code-settings-sync	Sha	3.2.7

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• DEBUG CONSOLE can not search word (#69200)
• Debug Console should support find (#4338)
• Cannot select all in debug console (#56159)
• Can't search in debug console (OS X insider build) (#24958)
• debug console shows top of window every time entering expression in console (#69207)

[bersbersbers]

• debug console shows top of window every time entering expression in console (#69207)

Yes, looks like #69207 is a duplicate of this one, although #69207 does not have specific reproduction steps. This one does.

Also, it looks like they investigated 1.32.0-insider, while I am still seeing this in 1.32.1. Also, I can repro this in the latest insider build with only the Python extension and no settings changed whatsoever (see below). Finally, I must admit finding repro steps was a bit difficult. So I am not fully convinced this issue is fixed, as implied by #69207.

Version: 1.33.0-insider
Commit: 49c10b916705b6006f04d0701875098b26d1d70b
Date: 2019-03-12T06:17:28.991Z
Electron: 3.1.6
Chrome: 66.0.3359.181
Node.js: 10.2.0
V8: 6.6.346.32
OS: Windows_NT x64 10.0.17763

[isidorn]

I can not reproduce this.
Can you attach a gif / video showing this
@DonJayamanne can you repro this using python?

[bersbersbers]

Sure, here's a GIF:

[isidorn]

I can not reproduce with node.
@DonJayamanne please try reproducing with python
@bersbersbers if you F1 > developer tools > put a breakpoint here what do you see as scrollTop, scrollHeight and renderHeight at the exact moment when the debug console scrolls unexpectedly?

[razhangwei]

I encountered exactly the same issue as @bersbersbers.

[isidorn]

@razhangwei then you can also try to answer the quesionts i asked @bersbersbers . Get your hands dirty and do some debugging. Thanks

[bersbersbers]

@bersbersbers if you F1 > developer tools > put a breakpoint here what do you see as scrollTop, scrollHeight and renderHeight at the exact moment when the debug console scrolls unexpectedly?

Breakpoint is hit twice per manual sys.exit().

After the first time manually entering sys.exit(), with the breakpoint hit at line 85:

scrollTop = 0, scrollHeight = 19, renderHeight = 214
scrollTop = 0, scrollHeight = 480, renderHeight = 214

After the second time manually entering sys.exit():

scrollTop = 266, scrollHeight = 480, renderHeight = 214
scrollTop = 266, scrollHeight = 80, renderHeight = 214 (+)

After (+), debug console is scrolled to top. I noticed that during (+), the debug console is empty, but not during any of the other breakpoint hits.

I double-checked: 80 is not a typo of 480, the above numbers are correct.

[DonJayamanne]

Yes, I too can replicate this issue on my Mac

[isidorn]

Ok, thanks for help everybody.
I can repro on my mac. Investigating...

[isidorn]

After investigating and discussion with @joaomoreno we figured out it is a dup of #68385