Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down

[Markus Armbruster]

"Chun Yan Liu" <address@hidden> writes:

>>>> On 9/6/2014 at 05:23 AM, in message
> <address@hidden>, Stefano
> Stabellini <address@hidden> wrote: 
>> On Fri, 5 Sep 2014, Chunyan Liu wrote: 
>> > Using xen tools 'xl vncviewer' with tigervnc (default on SLE-12), 
>> > found that: the display of the guest is unexpected while keep 
>> > pressing a key. We expect the same character multiple times, but 
>> > it prints only one time. This happens on a PV guest in text mode. 
>> >  
>> > After debugging, found that tigervnc sends repeated key down events 
>> > in this case, to differentiate from user pressing the same key many 
>> > times. Vnc server only prints the character when it finally receives 
>> > key up event. 
>>  
>> Is this actually how a vnc client should behave? 
>> How do the vnc client and server from realvnc behave in this regard 
>> (they are the reference implementation)? 
>
> VNC protocol doesn't specify how to handle key repetition. Tightvnc
> sends key-down&key-up repeatedly, but some example like RealVNC for
> Windows does the same thing - it sends only repeated key-down.
>
> Generally the VNC keyboard handling gives lot of space for interpretation
> and so the implementations differ.

If implementations differ, and QEMU already behaves like some of them,
then why change it?  What exactly gets fixed and what gets broken by the
proposed change?

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