[Bug] Multiple selections aren't rendered correctly

[wenfangdu]

Default dark theme config:

{
  "workbench.colorCustomizations": {
    "editor.selectionBackground": "#f008"
  }
}

Dracula config:

{
  "workbench.colorCustomizations": {
    "[Dracula]": {
      "editor.selectionBackground": "#bd93f980"
    }
  }
}

[wenfangdu]

@dsifford Please see https://github.com/microsoft/vscode/issues/127948#issuecomment-902540074:

The problem is that the Dracula theme defines the following color:

"editor.selectionHighlightBackground": "#424450",

This color is not using transparency, so the selection highlights are being rendered on top of the selection. This is an oversight with the theme. Please open an issue against the theme at https://github.com/dracula/visual-studio-code.

A workaround would be to customize that color to add some transparency to it:

"workbench.colorCustomizations": {
        "[Dracula]": {
            "editor.selectionBackground": "#bd93f980",
            "editor.selectionHighlightBackground": "#59595e88"
        }
    },

[dsifford]

@wenfangdu Try setting editor.selectionHighlightBackground to #8BE9FD30 and let me know if you are satisfied with that.

[wenfangdu]

@dsifford Can you give a color suggestion for editor.selectionBackground as well, so I can check them in comparison.

[wenfangdu]

This is the editor.selectionBackground & editor.selectionHighlightBackground comparison in the default dark theme:

This is the editor.selectionBackground & editor.selectionHighlightBackground comparison in the Dracula theme:

In the default dark theme, editor.selectionBackground is more obvious, whereas in the Dracula theme, editor.selectionHighlightBackground is more obvious, I think we should adjust both editor.selectionBackground & editor.selectionHighlightBackground and make editor.selectionBackground more standout.

As a side note, I do find my custom values are pretty neat, you can take them into account if needed:

{
  "editor.selectionBackground": "#5d627e",
  "editor.selectionHighlightBackground": "#59595e88"
}

[wenfangdu]

@dsifford @luxonauta @zenorocha Please reopen this issue, since #253 has been reverted.