Bug 267679 – <input type=checkbox switch> paints outside its box and the thumb is slightly misaligned on macOS

• Component: Forms
• Status: RESOLVED FIXED

[Anne van Kesteren]

As discovered in https://github.com/WebKit/WebKit/pull/22703#issuecomment-1890437523 <input type=checkbox> (and <input type=checkbox switch>) paint outside their box. Given it's only a couple points per pixel it's presumably shadows.

[Aditya Keerthi]

If it's the shadows this is not a bug.

If it's the control, then the implication is that these values are wrong:

```
static const int* checkboxMargins(NSControlSize controlSize)
{
    static const int margins[4][4] =
    {
        // top right bottom left
        { 2, 2, 2, 2 },
        { 2, 1, 2, 1 },
        { 0, 0, 1, 0 },
        { 2, 2, 2, 2 },
    };
    return margins[controlSize];
}
```

[Anne van Kesteren]

It's only the shadows.

Is there a better way to test that? I guess we should rename the test at least to clarify shadows can leak here.

[Radar WebKit Bug Importer]

<rdar://problem/121579531>

[Anne van Kesteren]

When I add masking for the thumb this goes away, so I suspect this was a real bug after all.

[Anne van Kesteren]

Pull request: https://github.com/WebKit/WebKit/pull/25582

[Anne van Kesteren]

Hmm, there's still some bleeding on the bots, but noticeably less with that patch.

[EWS]

Committed 275808@main (5381f48e7a04): <https://commits.webkit.org/275808@main>

Reviewed commits have been landed. Closing PR #25582 and removing active labels.