Re: [css3-background] Corner clipping and mouse events

On Jun 19, 2012, at 2:17 PM, Sylvain Galineau <sylvaing <at> microsoft.com> wrote:

> In section 5.3 [1] css3-background specifies that border-radius trims the 
> hit testing area, specifically:
> 
> # The content of replaced elements is always trimmed to the content edge 
> # curve. Also, the area outside the curve of the border edge does not accept 
> # mouse events on behalf of the element.
> 
> In our experience this behavior has proven to be of particular interest to 
> application design in a touch environment. While the UI guidelines for various 
> platforms recommend minimum touch target sizes for interactive elements those 
> generally assume square or rectangular control shapes. Thus, rounding elements 
> sized at or close to those guidelines can have an impact on real world hit-testing 
> with touch devices; in particular when creating a custom circular control such as 
> back or forward navigation buttons.
> 
> I suggest:
> 
> 1. Adding a note for authors such as:
> 
> # As border-radius reduces the interactive area of an element authors should make
> # sure the remaining hit-testing area conforms to recommended minima for the 
> # platforms they target; in particular, conforming to recommended minimum touch
> # target sizes may require larger widths and heights.
> 
> 2. Update 5.3. to change 'mouse events' to a less device-specific name. Pointer
> events?  Hit-testing events?
> 
>