Pointer grabs causing accessibility issues! Why not deprecate them?

Peter Hutterer mailinglists at who-t.net
Wed Apr 30 20:48:04 PDT 2008

Francesco Fumanti wrote:
> Eamon Walsh wrote:
>> Honestly I'm increasingly convinced that MPX is the best way to solve 
>> this problem, and related problems such as separating input by security 
>> level.
>> Create a new virtual mouse/keyboard that no one else can see and use to 
>> it to get the password.
> Wikipedia just informed me that MPX stands for Multi-Pointer X Server. ;-)
> But how does it solve the pointer grabbing issue: could an application 
> not simply grab the events of all pointers and keyboards?

grabbing in MPX is not quite as simple as in the normal X server 
(laughing is appropriate at this point).

Basically, a standard X app (i.e. not using the X Input Extension) can 
only grab a single device at a time. This device isn't always the same 
(it is predictable though).
Up to the point that if you have 10 devices, you may have 10 clients 
grabbing the pointer simultaneously, and each of them grabs a different 

XI apps can grab all devices, but they have to explicitly do so.


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