他プロセスのボタンClick

		public const int BM_CLICK = 0x00F5;

		[DllImport( "user32.dll", CharSet = CharSet.Auto, SetLastError = true )]
		static extern IntPtr FindWindowEx( IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow );
		[DllImport( "user32.dll", CharSet = CharSet.Auto, SetLastError = true )]
		private static extern IntPtr SendMessage( IntPtr hwnd, uint Msg, IntPtr wParam, IntPtr lParam );

		private void button1_Click( object sender, EventArgs e ) {
			IntPtr buttonHandle = FindWindowEx( Process.GetCurrentProcess().MainWindowHandle, IntPtr.Zero, null, "button4" );
			SendMessage( buttonHandle, BM_CLICK, IntPtr.Zero, IntPtr.Zero );
		}

		private void button4_Click( object sender, EventArgs e ) {
			MessageBox.Show( "Test" );
		}