Bugzilla

(In reply to Daniel Holbert [:dholbert] from comment #0)
> This is an incremental-layout bug -- if I adjust the testcase to have the cyan (abspos) element already-present up-front, or if I force frame reconstruction by temporarily toggling `display:none` on the `html` or `body` element, then the cyan element *mostly* covers up the red target area.  It's only when it's dynamically inserted that we end up giving it the completely wrong position.

Here's a "semi-reference case" to demonstrate this^.

This "semi-reference" ends up with the exact same DOM/styling as in testcase 1, but here we just append the abspos element *before* the first full layout.  We render this version somewhat better, with the cyan element *mostly* covering up the red area -- just shifted upwards a little bit (I think that slight shift is bug 489100 or something similar).

(In reply to Daniel Holbert [:dholbert] from comment #0)
> This is an incremental-layout bug -- if I adjust the testcase to have the cyan (abspos) element already-present up-front, or if I force frame reconstruction by temporarily toggling `display:none` on the `html` or `body` element, then the cyan element *mostly* covers up the red target area.  It's only when it's dynamically inserted that we end up giving it the completely wrong position.

Here's a "semi-reference case" to demonstrate this^.

This "semi-reference" ends up with the exact same DOM/styling as in testcase 1, but here we just append the abspos element *before* the first full layout.  We render this version somewhat better, with the cyan element *mostly* covering up the red area -- just shifted upwards a little bit (I think that slight offset is bug 489100 or something similar).