Bug 20217 - Expand touch-action property to include more of the values implemented by IE?

Hey folks,

Looking at this bug, we agree that pan-x and pan-y will add additional valuable use cases and also fall within the scope of the Working Group's charter.  These values allow the author to specify that the user agent may consume touches for scrolling a document along a particular axis.

The following text is what we'd like to propose to address this bug:

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pan-x
     The user agent MAY consume touches that begin on the element for the purposes of horizontally scrolling the element's nearest ancestor with horizontally scrollable content.
pan-y
     The user agent MAY consume touches that begin on the element for the purposes of vertically scrolling the element's nearest ancestor with vertically scrollable content.

Note: the terms "pan" and "scroll" are considered synonymous. Defining an interaction or gesture for triggering panning or scrolling, or for triggering behavior under auto, none or inherit values are out of scope for this specification.
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So the things to note here are:
  1. Pan-x/Pan-y describe the action, not the user input (e.g., touch gesture) to invoke a pan.  This is consistent with the WG charter.
  2.  A user input (e.g., touch gesture) that invokes Pan-x/Pan-y is determined by the user agent and out of scope of the specification per the WG charter.
  3.  A user agent has the freedom to define a user input that invokes Pan-x/Pan-y behavior, such as 2-finger drag, amount of pen pressure, or others.

I'll be happy to explain this further during our call tomorrow.

-Jacob