New subject: [Bug 59650] wayland: Modifier keys (Alt/Ctrl) get stuck when window loses focus due to race condition in release_all_keys()

April 12, 2026

http://bugs.winehq.org/show_bug.cgi?id=59650

            Bug ID: 59650
           Summary: wayland: Modifier keys (Alt/Ctrl) get stuck when
                    window loses focus due to race condition in
                    release_all_keys()
           Product: Wine
           Version: 11.6
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winewayland
          Assignee: wine-bugs@list.winehq.org
          Reporter: lldmakhbfcrmqyluns@nesopf.com
      Distribution: ---

Symptoms: When using native Wayland, pressing a global window manager shortcut
(like Alt+Tab or a custom Ctrl+Tab bound in KWin) causes the modifier key to
become permanently "stuck" inside the Wine application. For example, after
Alt+Tab out of the application and returning to it, the application behaves as
if Alt is still held down, immediately activating the window's top menu bar
(VK_MENU). The issue is absent in X Wayland.


Steps to reproduce:

    Run any 2 application in Wayland Wine.
    Press Alt+Tab several times to trigger windows switching.
    The application acts as if the Alt modifier is still pressed.

Technical Analysis (Root Cause): With WINEDEBUG=+waylanddrv,+keyboard,+key, the
log shows that Wayland sends the key press event, immediately followed by the
wl_keyboard.leave event. However, the key release is never generated by Wine.

The bug is a Race Condition located in dlls/winewayland.drv/wayland_keyboard.c
within the release_all_keys(HWND hwnd) function.

Currently, when keyboard_handle_leave is called, it triggers release_all_keys.
This function uses NtUserGetAsyncKeyboardState(state) to check which keys need
a synthetic KEYUP event:

c

static void release_all_keys(HWND hwnd) {
    BYTE state[256];
    NtUserGetAsyncKeyboardState(state);
    // ... sends KEYUP if state[vkey] & 0x80
}

Because Wayland events are processed very fast, the initial wl_keyboard.key
(pressed) event is sent to the Wine server queue via NtUserSendHardwareInput,
but the server has not processed it yet. When NtUserGetAsyncKeyboardState is
immediately called during the leave event, the server reports that the key is
not pressed. Therefore, release_all_keys skips sending the KEYUP event.
Milliseconds later, the server processes the KEYDOWN, and the key becomes stuck
forever.

Proposed Solution / Patch: The Wayland driver must not rely on the asynchronous
Wine server state to release keys during focus loss. It should maintain its own
local array of physically pressed evdev keys and release them accordingly.

Here is a proposed patch to fix this issue:

diff

--- a/dlls/winewayland.drv/wayland_keyboard.c
+++ b/dlls/winewayland.drv/wayland_keyboard.c
@@ -79,6 +79,9 @@
 static struct rxkb_context *rxkb_context;
 static HKL keyboard_hkl; /* the HKL matching the currently active xkb group */

+/* Local state to track physically pressed keys to avoid race conditions with
wine server */
+static BYTE wayland_pressed_keys[KEY_MAX];
+
 void activate_keyboard_hkl(HWND hwnd, BOOL ime)
 {
     HKL hkl = ime && !is_ime_hkl(keyboard_hkl) ?
get_ime_hkl(LOWORD(keyboard_hkl)) : keyboard_hkl;
@@ -430,24 +433,23 @@

 static void release_all_keys(HWND hwnd)
 {
-    BYTE state[256];
-    int vkey;
-    INPUT input = {.type = INPUT_KEYBOARD};
-
-    NtUserGetAsyncKeyboardState(state);
-
-    for (vkey = 1; vkey < 256; vkey++)
+    int key;
+    
+    for (key = 0; key < ARRAY_SIZE(wayland_pressed_keys); key++)
     {
-        /* Skip mouse buttons. */
-        if (vkey < 7 && vkey != VK_CANCEL) continue;
-        /* Skip left/right-agnostic modifier vkeys. */
-        if (vkey == VK_SHIFT || vkey == VK_CONTROL || vkey == VK_MENU)
continue;
-
-        if (state[vkey] & 0x80)
+        if (wayland_pressed_keys[key])
         {
-            UINT scan = NtUserMapVirtualKeyEx(vkey, MAPVK_VK_TO_VSC_EX,
-                                              keyboard_hkl);
-            input.ki.wVk = vkey;
+            UINT scan = key2scan(key);
+            INPUT input = {0};
+
+            if (key == KEY_RIGHTALT) send_right_control(hwnd,
WL_KEYBOARD_KEY_STATE_RELEASED);
+
+            input.type = INPUT_KEYBOARD;
+            input.ki.wScan = (scan & 0x300) ? scan + 0xdf00 : scan;
+            input.ki.dwFlags = KEYEVENTF_SCANCODE | KEYEVENTF_KEYUP;
+            if (scan & ~0xff) input.ki.dwFlags |= KEYEVENTF_EXTENDEDKEY;
+
+            NtUserSendHardwareInput(hwnd, 0, &input, 0);
+            
+            wayland_pressed_keys[key] = 0;
         }
     }
 }
@@ -524,6 +526,9 @@

     InterlockedExchange(&process_wayland.input_serial, serial);

+    if (key < ARRAY_SIZE(wayland_pressed_keys))
+        wayland_pressed_keys[key] = (state == WL_KEYBOARD_KEY_STATE_PRESSED);
+
     if (!(hwnd = wayland_keyboard_get_focused_hwnd())) return;

     TRACE_(key)("serial=%u hwnd=%p key=%d scan=%#x state=%#x\n", serial, hwnd,
key, scan, state);

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[Bug 59650] New: wayland: Modifier keys (Alt/Ctrl) get stuck when window loses focus due to race condition in release_all_keys()

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