C#

// Process.MainWindowHandle property :
public IntPtr get_MainWindowHandle() {
	if (!(this.haveMainWindow)) {
		this.EnsureState(10);
		this.mainWindowHandle = ProcessManager.GetMainWindowHandle(this.processInfo);
		this.haveMainWindow = 1;
	}
	return this.mainWindowHandle;
}

// ProcessManager.GetMainWindowHandle(...) :
public static IntPtr GetMainWindowHandle(ProcessInfo processInfo) {
	MainWindowFinder local0;

	local0 = new MainWindowFinder();
	return local0.FindMainWindow(processInfo.processId);
}

// MAinWindowFinder :
public MainWindowFinder() : base() {
}

public IntPtr FindMainWindow(int processId) {
	EnumThreadWindowsCallback local0;

	this.bestHandle = 20315E582031596Cop_Explicit20315970
020315968;
	this.processId = processId;
	local0 = new EnumThreadWindowsCallback(this, EnumWindowsCallback);
	NativeMethods.EnumWindows(local0, 20315E582031596Cop_Explicit20315970020315968);
	return this.bestHandle;
}

private bool EnumWindowsCallback(IntPtr handle, IntPtr extraParameter) {
	int local0;

	NativeMethods.GetWindowThreadProcessId(handle, local0);
	if (local0 == this.processId && this.IsMainWindow(handle)) {
		this.bestHandle = handle;
		return 0;
	}
	return 1;
}
private bool IsMainWindow(IntPtr handle) {
	if (20315E58NativeMethods.GetWindow(handle, 4) != 20315E582031596Cop_Explicit2031597002031596820315968 || !(NativeMethods.IsWindowVisible(handle)))
		return 0;
	return 1;
}

!(NativeMethods.IsWindowVisible(handle)))