Try position nerd font and powerline glyphs absolutely in the DOM renderer

[Tyriar]

From https://github.com/microsoft/vscode/issues/120129#issuecomment-812724879

The DOM renderer works a little differently, to get cells to align perfectly they are laid our using inline-block and regular rely on the regular flow of the page as opposed to absolute positioning for performance reasons. I wonder if we could take the nerd font glyph ranges and the powerlines glyph ranges, and handle them specially. Positioning absolute won't work but I wonder if we could do some something using :before { content: '' } so that it could be positioned absolutely on top of the cell 🤔

Surprisingly I didn't see the line on my tests, maybe it's only on certain font sizes or something.

[Mellbourn]

I said in the original ticket:

In Insiders, renderType is removed, so, as you say, you can't force it explicitly. If I set terminal.integrated.gpuAcceleration to off, I get this:

Here there is still a vertical line. Also, the double-width Nerd Fonts glyphs look cut off to single character width.

Some more info about my VSCode in case the issue is hard to reproduce:

Version: 1.56.0-insider
Commit: 550035808407c15252e581e8abe1b820b9d311ee
Date: 2021-04-02T05:23:43.134Z (16 hrs ago)
Electron: 11.4.1
Chrome: 87.0.4280.141
Node.js: 12.18.3
V8: 8.7.220.31-electron.0
OS: Darwin arm64 20.3.0

These are my relevant font settings:

  "terminal.integrated.gpuAcceleration": "off",
  "terminal.integrated.fontFamily": "Cascadia Code PL, Delugia Nerd Font Book, CaskaydiaCove Nerd Font, Menlo, monospace",
  "editor.fontLigatures": "'ss02', 'ss03', 'ss05', 'ss07'",
  "editor.fontWeight": "500",
  "editor.fontSize": 12,
  "terminal.integrated.fontSize": 12,

Simplifying these two settings made no difference:

  "terminal.integrated.fontFamily": "Delugia Nerd Font Book",
  "editor.fontLigatures": "off",

The occurrence of the vertical lines seem dependent on font size! 10 has two lines

11 has one line

12 has one

13 has one on each end

14 has a very thin line

The position of the vertical lines kept changing as I increased the font. The lines seem to be approximately constant width, so as the font grows they become less and less noticeable.