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Fix the crash leaving fullscreen on Windows #39

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Merged
catchouli merged 1 commit into from
Oct 29, 2026
Merged

Fix the crash leaving fullscreen on Windows #39

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21 changes: 15 additions & 6 deletions crates/flex-app/src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,20 +31,29 @@ use std::path::PathBuf;

use eframe::egui;

/// Initialises COM on the UI thread for the life of the app (never uninitialised).
/// Initialises COM on the UI thread for the life of the app (never uninitialised), and
/// keeps the taskbar's COM library loaded for good.
///
/// winit creates a COM taskbar object the first time the window goes fullscreen and reuses
/// it afterwards. If COM on this thread is torn down in between (libmpv initialises and
/// uninitialises COM as players come and go), that object is freed and leaving fullscreen
/// crashes with an access violation. Holding our own reference keeps COM, and the object,
/// alive.
/// winit creates a COM taskbar object (from explorerframe.dll) the first time the window
/// goes fullscreen and reuses it afterwards. Crash dumps from the TV PC showed that
/// explorerframe.dll still gets unloaded in between, even with COM kept alive here, and
/// the next fullscreen change then crashes calling into it. Pinning the DLL means it can't
/// be unloaded, whatever asks for that.
#[cfg(windows)]
fn keep_com_alive() {
use windows_sys::Win32::System::Com::{COINIT_APARTMENTTHREADED, COINIT_DISABLE_OLE1DDE, CoInitializeEx};
use windows_sys::Win32::System::LibraryLoader::{GET_MODULE_HANDLE_EX_FLAG_PIN, GetModuleHandleExW, LoadLibraryW};
let hr = unsafe { CoInitializeEx(std::ptr::null(), (COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE) as u32) };
if hr < 0 {
log::warn!("couldn't initialise COM on the UI thread: {hr:#x}");
}
let name: Vec<u16> = "explorerframe.dll".encode_utf16().chain([0]).collect();
let mut module = std::ptr::null_mut();
// Safety: `name` is a NUL-terminated wide string that outlives both calls.
let pinned = unsafe { !LoadLibraryW(name.as_ptr()).is_null() && GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_PIN, name.as_ptr(), &mut module) != 0 };
if !pinned {
log::warn!("couldn't keep explorerframe.dll loaded: leaving fullscreen may crash");
}
}

/// `--test-crash`: crashes a few seconds after starting (once settings are loaded), to
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