C#

public bool WaitForExit(int milliseconds) {
	IntPtr local0;
	bool local1;
	int local2;

	local0 = 20315E582031596Cop_Explicit20315970020315968;
	try {
		local0 = this.GetProcessHandle(1048576, false);
		if (20315E58local0 == NativeMethods.INVALID_HANDLE_VALUE20315968)
			local1 = true;
		else {
			local2 = NativeMethods.WaitForSingleObject(local0, milliseconds);
			if (local2 == 0)
				local1 = true;
			else {
				if (local2 == 258)
					local1 = false;
				else
					throw new Win32Exception();
			}
		}
	}
	finally {
		this.ReleaseProcessHandle(local0);
	}
	if (local1 && this.watchForExit)
		this.RaiseOnExited();
	return local1;
}

public void Kill() {
	IntPtr local0;

	local0 = 20315E582031596Cop_Explicit20315970020315968;
	try {
		local0 = this.GetProcessHandle(1);
		if (!(NativeMethods.TerminateProcess(local0, -1)))
			throw new Win32Exception();
	}
	finally {
		this.ReleaseProcessHandle(local0);
	}
}

[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern IntPtr SendMessage(IntPtr hWnd, int msg, int wParam, IntPtr lParam);

public const int WM_SYSCOMMAND = 0x0112;
public const int SC_CLOSE = 0xF060;
public const int WM_QUIT = 0x0012;
NativeWIN32.SendMessage( hWnd, WM_QUIT, 0, 0);

or

NativeWIN32.SendMessage(hWnd, NativeWIN32.WM_SYSCOMMAND, NativeWIN32.SC_CLOSE, IntPtr.Zero);

Dim wnd As System.IntPtr<br />
wnd = Process.MainWindowHandle<br />
hWnd = wnd.ToInt32<br />
If hWnd <> 0 Then<br />
    Call SendMessage(hWnd, WM_CLOSE, 0, 0)<br />
End If

// 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)))