ui/sdl2: reenable the SDL2 Windows keyboard hook procedure

Windows only:

The libSDL2 Windows message loop needs the libSDL2 Windows low
level keyboard hook procedure to grab the left and right Windows
keys correctly. Reenable the SDL2 Windows keyboard hook procedure.

Since SDL2 2.30.4 the SDL2 keyboard hook procedure also filters
out the special left Control key event for every Alt Gr key event
on keyboards with an international layout. This means the QEMU low
level keyboard hook procedure is no longer needed. Remove the QEMU
Windows keyboard hook procedure.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2139
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2323
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Link: https://lore.kernel.org/r/20241231115950.6732-1-vr_qemu@t-online.de
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

ui/meson.build

@@ -120,10 +120,6 @@ if gtk.found()
 endif
 
 if sdl.found()
-  if host_os == 'windows'
-    system_ss.add(files('win32-kbd-hook.c'))
-  endif
-
   sdl_ss = ss.source_set()
   sdl_ss.add(sdl, sdl_image, pixman, glib, files(
     'sdl2-2d.c',

ui/sdl2.c

@@ -32,7 +32,6 @@
 #include "system/runstate.h"
 #include "system/runstate-action.h"
 #include "system/system.h"
-#include "ui/win32-kbd-hook.h"
 #include "qemu/log.h"
 #include "qemu-main.h"
 
@@ -263,7 +262,6 @@ static void sdl_grab_start(struct sdl2_console *scon)
     }
     SDL_SetWindowGrab(scon->real_window, SDL_TRUE);
     gui_grab = 1;
-    win32_kbd_set_grab(true);
     sdl_update_caption(scon);
 }
 
@@ -271,7 +269,6 @@ static void sdl_grab_end(struct sdl2_console *scon)
 {
     SDL_SetWindowGrab(scon->real_window, SDL_FALSE);
     gui_grab = 0;
-    win32_kbd_set_grab(false);
     sdl_show_cursor(scon);
     sdl_update_caption(scon);
 }
@@ -372,19 +369,6 @@ static int get_mod_state(void)
     }
 }
 
-static void *sdl2_win32_get_hwnd(struct sdl2_console *scon)
-{
-#ifdef CONFIG_WIN32
-    SDL_SysWMinfo info;
-
-    SDL_VERSION(&info.version);
-    if (SDL_GetWindowWMInfo(scon->real_window, &info)) {
-        return info.info.win.window;
-    }
-#endif
-    return NULL;
-}
-
 static void handle_keydown(SDL_Event *ev)
 {
     int win;
@@ -609,10 +593,6 @@ static void handle_windowevent(SDL_Event *ev)
         sdl2_redraw(scon);
         break;
     case SDL_WINDOWEVENT_FOCUS_GAINED:
-        win32_kbd_set_grab(gui_grab);
-        if (qemu_console_is_graphic(scon->dcl.con)) {
-            win32_kbd_set_window(sdl2_win32_get_hwnd(scon));
-        }
         /* fall through */
     case SDL_WINDOWEVENT_ENTER:
         if (!gui_grab && (qemu_input_is_absolute(scon->dcl.con) || absolute_enabled)) {
@@ -628,9 +608,6 @@ static void handle_windowevent(SDL_Event *ev)
         scon->ignore_hotkeys = get_mod_state();
         break;
     case SDL_WINDOWEVENT_FOCUS_LOST:
-        if (qemu_console_is_graphic(scon->dcl.con)) {
-            win32_kbd_set_window(NULL);
-        }
         if (gui_grab && !gui_fullscreen) {
             sdl_grab_end(scon);
         }
@@ -870,10 +847,7 @@ 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 procedure 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