libinput requirements for feature parity with X

[Bill Spitzak]

Ping Cheng wrote:

>     graphics tablets:
>     * extended axis event support
>     * tool change notification (could be just button events? not sure)
> 
> 
> Will tool id, serial number, and tool type be supported here?

Shouldn't each tool be a different pointing device? It at least needs to 
know which tool is being used when moving it, it can't be deferred until 
the first button is being pushed.

Are tablets capable of handling more than one tool at a time? If this is 
at all plausable I think they all have to be different pointers since 
otherwise there is no way to indicate which x/y position is which tool. 
Otherwise I guess a "tool changed" event would work.