ISSUE-154: Clarify diagonal wheel deltas on wheel events

multiple wheel deltas

Clarify diagonal wheel deltas on wheel events

HISTORICAL: DOM3 Events [All Bugs and Issues use Bugzilla:]
Raised by:
Doug Schepers
Opened on:
David Flanagan <>:
The current Editor's Draft has this description of the deltaMode
property of WheelEvent

> deltaMode of type unsigned long, readonly
> The deltaMode attribute contains an indication of to indicate the units of measurement for the delta values. The default value is DOM_DELTA_PIXEL (pixels). The value of deltaMode may be different for each of deltaX, deltaY, and deltaZ, based on system configuration.

Does the fact that deltaMode can be different for the X, Y, and Z axes
mean that browsers always generate separate events for each axis?

If a user moves the mouse wheel "diagonally" to scroll down and to the
right, is the browser required to generate one wheel event, two wheel
events, or can it do either one of those things?

I think the spec ought to be clarified to explain this.
Related Actions Items:
No related actions
Related emails:
  1. Minutes, DOM3 Events telcon, 04 Feb 2011 (from on 2011-02-06)
  2. ISSUE-154 (multiple wheel deltas): Clarify diagonal wheel deltas on wheel events [DOM3 Events] (from on 2010-10-20)

Related notes:

Revision 1.168. Clarified that diagonal wheel deltas can come either as separate events for each axis or as a single event with multiple non-zero axes.

Jacob Rossi, 24 Apr 2011, 23:17:26

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