We do not want to traverse inside native anonymous elements, but we
should still be able to skip over generated content, to avoid getting
stuck on such images.
The caret movement code already handles unselectable text frames if we
happen to land in the middle of one in nsTextFrame::PeekOffsetCharacter/Word.
However, when performing frame traversal to find the next frame to jump
to, we don't remember if we skipped over an unselectable frame, which causes
us to jump one offset too much when the caret is on the boundary of
selectable and unselectable content. The test cases demonstrate the
scenario. Note that an <img alt=foo> is implemented by adding a
generated content to the inline frame representing it, so as far as
the caret movement code is concerned, both test cases are treated similarly.
Note that we need to do this only when moving the selection, and not
when extending it. We are adding an aExtend argument to
nsPeekOffsetStruct's constructor in order to be able to special case
that.
We do not want to traverse inside native anonymous elements, but we
should still be able to skip over generated content, to avoid getting
stuck on such images.
The caret movement code already handles unselectable text frames if we
happen to land in the middle of one in nsTextFrame::PeekOffsetCharacter/Word.
However, when performing frame traversal to find the next frame to jump
to, we don't remember if we skipped over an unselectable frame, which causes
us to jump one offset too much when the caret is on the boundary of
selectable and unselectable content. The test cases demonstrate the
scenario. Note that an <img alt=foo> is implemented by adding a
generated content to the inline frame representing it, so as far as
the caret movement code is concerned, both test cases are treated similarly.
Note that we need to do this only when moving the selection, and not
when extending it. We are adding an aExtend argument to
nsPeekOffsetStruct's constructor in order to be able to special case
that.
The content inside an editable region is either editable itself, or
is inside a contenteditable="false" subtree. In the first case,
it should not be focusable since it is editable. In the second
case, it should not be focusable since the entire non-editable
region is treated as a special single entity for the purposes of
selection and caret movement, and having something focusable in
the middle of such a subtree breaks that model.
The content inside an editable region is either editable itself, or
is inside a contenteditable="false" subtree. In the first case,
it should not be focusable since it is editable. In the second
case, it should not be focusable since the entire non-editable
region is treated as a special single entity for the purposes of
selection and caret movement, and having something focusable in
the middle of such a subtree breaks that model.
The change to GetAfterFrameForContent prevents the reframe that is part
of the chain of events leading to this bug, and thus fixes the bug on
its own. The change to GetBeforeFrameForContent seems desirable for
symmetry.
Note that patch 6 also independently fixes the reported bug.
This probably needs somewhat careful review. We should examine:
(1) what the rules for calling nsLayoutUtils::GetBeforeFrame and
nsLayoutUtils::GetAfterFrame are, and whether both (or neither)
need to be patched.
(2) What the rules are for which frame the GenConProperty() lives on,
and whether we should adjust nsIFrame::GetGenConPseudos() to either
do something more intelligent, or assert about callers.
(We should probably clean up some of these things in a followup bug.)
Since the symptom of this bug is (once patch 4 is in the tree) only
causing extra reframes, it can only be tested using the new API (from
bug 1115691) for observing reframes. I confirmed that the test for this
bug fails without the patch and passes with the patch (as noted by the
removal of its todo annotation).
This patch fixes the assertion on layout/generic/crashtests/600100.xhtml,
though I haven't investigated why.
This patch is not needed to fix the bug, but it seems like it's probably
desirable. It's not needed for this bug because
MaybeReframeForBeforePseudo and MaybeReframeForAfterPseudo are already
called (by ElementRestyler::RestyleChildren) on only the first and last
continuation or ib-split sibling with the same style. So this patch
should only actually change anything for cases like a block-in-inline
split whose initial inline part is inside of a ::first-line (where
different parts of the block-in-inline split chain have different style).
Since the symptom of this bug is (once patch 6 is in the tree) only
causing extra reframes, it can only be tested using the new API (from
bug 1115691) for observing reframes. I confirmed that the test for this
bug fails without the patch and passes with the patch (as noted by the
removal of its todo annotation).
We are white-listing the existing set of tests that use setTimeout
like this. Hopefully these tests will be investigated and fixed
in the future, so that we can narrow down the white-list.
This check is only turned on for mochitest-plain for now.
