927189 - Add flag to nsLayoutUtils::GetFramesForArea to return POINTER_EVENTS_NONE styled frames

Status: NEW

(Core :: Web Painting, defect)

Description

[Eitan Isaacson [:eeejay]]

Currently, GetFramesForArea uses nsDisplayList::HitTest that ignores frames that don't receive pointer events. This is the correct behavior for most uses regarding pointers.

We will need a way to know in accessibility if a frame is obscured by another frame. The way I tried to do this is to use GetFramesForArea with a 1x1 rect in the accessible's frame center, and to check all returned frames, before the accessible frame, to see if their bounds fully contain the accessible's bounds.

If the accessible frame does not take pointer events, it will not be in the list of returned frames from GetFramesForArea, and thus, we won't know when to stop the search, and when we are looking at candidates below the accessible frame's z-index.