Re: [PATCH] ui/sdl2: disable SDL_HINT_GRAB_KEYBOARD on Windows

[Thomas Huth <thuth@redhat.com>]

On 18/04/2023 08.28, Volker Rümelin wrote:
> Windows sends an extra left control key up/down input event for
> every right alt key up/down input event for keyboards with
> international layout. Since commit 830473455f ("ui/sdl2: fix
> handling of AltGr key on Windows") QEMU uses a Windows low level
> keyboard hook procedure to reliably filter out the special left
> control key and to grab the keyboard on Windows.
> 
> The SDL2 version 2.0.16 introduced its own Windows low level
> keyboard hook procedure to grab the keyboard. Windows calls this
> callback before the QEMU keyboard hook procedure. This disables
> the special left control key filter when the keyboard is grabbed.
> 
> To fix the problem, disable the SDL2 Windows low level keyboard
> hook procedure.
> 
> Reported-by: Bernhard Beschow <shentey@gmail.com>
> Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
> ---
>   ui/sdl2.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/ui/sdl2.c b/ui/sdl2.c
> index 00aadfae37..9d703200bf 100644
> --- a/ui/sdl2.c
> +++ b/ui/sdl2.c
> @@ -855,7 +855,10 @@ static void sdl2_display_init(DisplayState *ds, DisplayOptions *o)
>   #ifdef SDL_HINT_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR /* only available since SDL 2.0.8 */
>       SDL_SetHint(SDL_HINT_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR, "0");
>   #endif
> +#ifndef CONFIG_WIN32
> +    /* QEMU uses its own low level keyboard hook procecure on Windows */
>       SDL_SetHint(SDL_HINT_GRAB_KEYBOARD, "1");
> +#endif
>   #ifdef SDL_HINT_ALLOW_ALT_TAB_WHILE_GRABBED
>       SDL_SetHint(SDL_HINT_ALLOW_ALT_TAB_WHILE_GRABBED, "0");
>   #endif

Reviewed-by: Thomas Huth <thuth@redhat.com>