Scrollable subdocument's area not part of root scrollable layer's dispatch-to-content region on page load

RESOLVED DUPLICATE of bug 1154478

Status

()

Core
Layout
RESOLVED DUPLICATE of bug 1154478
3 years ago
3 years ago

People

(Reporter: botond, Assigned: botond)

Tracking

Trunk
x86_64
Linux
Points:
---

Firefox Tracking Flags

(firefox40 affected)

Details

(Whiteboard: [gfx-noted])

(Assignee)

Description

3 years ago
STR:
  1. Load http://people.mozilla.org/~bballo/iframe.html with APZ enabled
  2. Observe that the iframe is initially not layerized.
     (This may or may not be intentional - see bug 1151663 - but let's
     assume for now it is.)
  3. Position the mouse over the iframe
  4. Scroll down with the mouse wheel

Expected results:
  The iframe scrolls. (The expected mechanism for this is that the
  iframe is contained inside the dispatch-to-content region of the
  root scroll frame, so APZ waits for a set-target-apzc notification
  before scrolling. Content layerizes the iframe, and sets it as
  the target rather than the root scroll frame.)

Actual results:
  The page scrolls initially. (Once the iframe is layerized, it
  then starts scrolling instead.)

(This is also reproducible with a <div> instead of an <iframe> [1]).

[1] http://people.mozilla.org/~bballo/div.html
(Assignee)

Updated

3 years ago
Whiteboard: [gfx-noted]
(Assignee)

Comment 1

3 years ago
Still reproductible on a recent nightly. I will investigate.
Assignee: nobody → botond
(Assignee)

Comment 2

3 years ago
Looks like initially, the iframe's area is not included in the dispatch-to-content region of the root scrollable layer.
(Assignee)

Updated

3 years ago
Component: Panning and Zooming → Layout
Summary: Wrong initial target for mouse wheel scroll when subframe is not layerized → Scrollable subdocument's area not part of root scrollable layer's dispatch-to-content region on page load
(Assignee)

Comment 3

3 years ago
Markus mentioned that the failure of dom/events/test/test_bug574663.html with APZ enabled (which was worked around for the APZ-windows-nightly-enabling) could have the same cause.
(Assignee)

Comment 5

3 years ago
The problem is that I was testing with the event-regions pref off.

Bug 1137267 modified nsDisplayListBuilder::IsBuildingLayerEventRegions() to return true if APZ is enabled, even if the event-regions pref is off, but the place in layout code that added inactive scroll frames to the event-regions was checking gfxPrefs::LayoutEventRegionsEnabled() directly rather than checking nsDisplayListBuilder::IsBuildingLayerEventRegions().
(Assignee)

Updated

3 years ago
See Also: → bug 1137267
(Assignee)

Comment 6

3 years ago
Looks like this is fixed by the patch in bug 1154478.
Status: NEW → RESOLVED
Last Resolved: 3 years ago
Resolution: --- → DUPLICATE
Duplicate of bug: 1154478
You need to log in before you can comment on or make changes to this bug.