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windows: fix layout-switch freeze (Punto Switcher) via WM_INPUTLANGCHANGE #15

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windows: fix layout-switch freeze (Punto Switcher) via WM_INPUTLANGCHANGE #15

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windows: fix deadlock on keyboard layout switch (PuntoSwitcher, IME)
chilango74 May 26, 2026
a8a69b5
windows: fix layout-switch freeze by refreshing layout cache on WM_IN…
chilango74 May 28, 2026
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3 changes: 3 additions & 0 deletions src/changelog/unreleased.md
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Original file line number Diff line number Diff line change
Expand Up @@ -217,6 +217,9 @@ changelog entry.

### Fixed

- On Windows, fix freeze when switching keyboard layout with tools like Punto Switcher. The
`WM_INPUTLANGCHANGE` message is now handled to refresh the cached keyboard layout, while still
deferring to `DefWindowProc` for normal propagation.
- On Orbital, `MonitorHandle::name()` now returns `None` instead of a dummy name.
- On iOS, fixed `SurfaceResized` and `Window::surface_size` not reporting the size of the actual surface.
- On macOS, fixed the scancode conversion for audio volume keys.
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27 changes: 21 additions & 6 deletions src/platform_impl/windows/event_loop.rs
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Expand Up @@ -49,12 +49,12 @@ use windows_sys::Win32::UI::WindowsAndMessaging::{
WMSZ_BOTTOMRIGHT, WMSZ_LEFT, WMSZ_RIGHT, WMSZ_TOP, WMSZ_TOPLEFT, WMSZ_TOPRIGHT,
WM_CAPTURECHANGED, WM_CLOSE, WM_CREATE, WM_DESTROY, WM_DPICHANGED, WM_ENTERSIZEMOVE,
WM_EXITSIZEMOVE, WM_GETMINMAXINFO, WM_IME_COMPOSITION, WM_IME_ENDCOMPOSITION,
WM_IME_SETCONTEXT, WM_IME_STARTCOMPOSITION, WM_INPUT, WM_KEYDOWN, WM_KEYUP, WM_KILLFOCUS,
WM_LBUTTONDOWN, WM_LBUTTONUP, WM_MBUTTONDOWN, WM_MBUTTONUP, WM_MENUCHAR, WM_MOUSEHWHEEL,
WM_MOUSEMOVE, WM_MOUSEWHEEL, WM_NCACTIVATE, WM_NCCALCSIZE, WM_NCCREATE, WM_NCDESTROY,
WM_NCLBUTTONDOWN, WM_PAINT, WM_POINTERDOWN, WM_POINTERUP, WM_POINTERUPDATE, WM_RBUTTONDOWN,
WM_RBUTTONUP, WM_SETCURSOR, WM_SETFOCUS, WM_SETTINGCHANGE, WM_SIZE, WM_SIZING, WM_SYSCOMMAND,
WM_SYSKEYDOWN, WM_SYSKEYUP, WM_TOUCH, WM_WINDOWPOSCHANGED, WM_WINDOWPOSCHANGING,
WM_IME_SETCONTEXT, WM_IME_STARTCOMPOSITION, WM_INPUT, WM_INPUTLANGCHANGE, WM_KEYDOWN, WM_KEYUP,
WM_KILLFOCUS, WM_LBUTTONDOWN, WM_LBUTTONUP, WM_MBUTTONDOWN, WM_MBUTTONUP, WM_MENUCHAR,
WM_MOUSEHWHEEL, WM_MOUSEMOVE, WM_MOUSEWHEEL, WM_NCACTIVATE, WM_NCCALCSIZE, WM_NCCREATE,
WM_NCDESTROY, WM_NCLBUTTONDOWN, WM_PAINT, WM_POINTERDOWN, WM_POINTERUP, WM_POINTERUPDATE,
WM_RBUTTONDOWN, WM_RBUTTONUP, WM_SETCURSOR, WM_SETFOCUS, WM_SETTINGCHANGE, WM_SIZE, WM_SIZING,
WM_SYSCOMMAND, WM_SYSKEYDOWN, WM_SYSKEYUP, WM_TOUCH, WM_WINDOWPOSCHANGED, WM_WINDOWPOSCHANGING,
WM_XBUTTONDOWN, WM_XBUTTONUP, WNDCLASSEXW, WS_EX_LAYERED, WS_EX_NOACTIVATE, WS_EX_TOOLWINDOW,
WS_EX_TRANSPARENT, WS_OVERLAPPED, WS_POPUP, WS_VISIBLE,
};
Expand Down Expand Up @@ -1569,6 +1569,21 @@ unsafe fn public_window_callback_inner(
result = ProcResult::DefWindowProc(wparam);
},

WM_INPUTLANGCHANGE => {
// Refresh the cached keyboard layout for the newly activated input
// language. This message is sent (by Windows or by layout switchers
// such as Punto Switcher) after the layout changes. Refreshing the
// cache here prevents a freeze that otherwise occurs when switching
// layout via such tools. We still defer to `DefWindowProc` so the
// message keeps propagating to first-level child windows, as the
// Win32 documentation requires.
{
let mut layouts = LAYOUT_CACHE.lock().unwrap();
layouts.get_current_layout();
}
result = ProcResult::DefWindowProc(wparam);
},
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@acarl005 acarl005 May 27, 2026 •
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Are you sure we aren't breaking something by preventing WM_INPUTLANGCHANGE from falling back to DefWindowProc? The official microsoft docs say:

"You should make any application-specific settings and pass the message to the DefWindowProc function, which passes the message to all first-level child windows"


// this is necessary for us to maintain minimize/restore state
WM_SYSCOMMAND => {
if wparam == SC_RESTORE as usize {
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