Re: [Qemu-devel] alt-gr on Windows

[Andreas Färber]

Hi,

Am 18.12.2014 um 12:55 schrieb Kevin Wolf:
> Am 17.12.2014 um 01:11 hat Thebault, Remi geschrieben:
>> This is not the first post on this topic, but I haven't seen any
>> solution about it.
>> I tested so far linux guest on windows host and the AltGr key is
>> dead in the guest. (using git master branch)
>>
>> On french keyboard, the keys to yield the bar "|" are alt-gr + 6.
>> when executing this combination on keyboard, Windows generates this:
>>     - L-CTRL
>>     - R-ALT
>>     - 6
>>
>> in Qemu (only digged gtk UI so far), pressing alt-gr + 6 generates
>> the following trace
>>     - L-CTRL
>>     - L-ALT   <-- note left here
>>     - 6
>>
>> This comes from the Win32 call MapVirtualKey in gtk.c that maps to
>> scancodes without left/right distinction.
>> Even when sending the right alt to the guest, the alt-gr key remains
>> dead because of ctrl being virtually pressed. I found out however
>> that if R-ALT + 6 is sent without the ctrl key, the guest finally
>> recognize it and prints the bar, @, # and other [}{].
>>
>> To make things easier, Windows delivers the ctrl code before the alt
>> code, so catching it cleanly before delivery to the guest is
>> probably tough.
>> I could however come to an easy and quick fix with sending the "ctrl
>> up" signal to the guest before the "r-alt down" is sent.
>>
>> My current code do not handle all corner cases (eg: turbo mode) and
>> only fixes the gtk ui, but would such fix be accepted in the repo?
>> Would this break somehow the windows guest on windows host?
> 
> CCing Stefan Weil, who is both the Windows maintainer and the author of
> commit 2777ccc5, which introduced the MapVirtualKey() call. As there is
> a special case for Alt Gr in the code, I suppose he had this working
> back then.
> 
> From what I understand (which isn't much when it's about Windows), it
> seems very unlikely to me that the change would break anything that is
> working today; but you should probably give it some testing before
> posting a patch.

Tim and colleagues have been investigating some AltGr issues on Linux /
NoVNC as well, so it may well have been broken before Stefan's commit.

Regards,
Andreas

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