1658009 - Dispatch-to-content mechanism is broken when pinch-zooming via mousewheel+modifier

Status: NEW

(Core :: Panning and Zooming, defect, P2)

Description

[Botond Ballo [:botond]]

STR

1. Run Firefox with desktop zooming enabled (now default on nightly)
2. In about:config set mousewheel.with_alt.action=5
3. Load any page that wants to handle pinch gestures itself, such as Google Maps
4. Zoom in with alt+mousewheel

Expected results

The gesture is handled by the page (e.g. Google Maps zooms in and shows a more detailed map).

Actual results

The gesture is handled by the browser (e.g. we just repaint the same-detail map image larger).

Comment 1

[Botond Ballo [:botond]]

The codepath that handles pinch-zooming via mousewheel+modifier does not handle dispatch-to-content at all -- it just treats the synthesized events as confirmed.

Comment 2

[Botond Ballo [:botond]]

I marked this as blocking desktop-zoom-post since we're not shipping mousewheel+modifier zooming initially, but we may want to fix it sooner because mousewheel+modifier is useful for reproing zooming issues locally (particularly on Linux).