func NewComboBox(parent Container) (*ComboBox, error) {
	cb, err := newComboBoxWithStyle(parent, win.CBS_DROPDOWN)
	if err != nil {
		return nil, err
	}

	editHwnd := win.GetWindow(cb.hWnd, win.GW_CHILD)

	win.SetWindowLongPtr(editHwnd, win.GWLP_USERDATA, uintptr(unsafe.Pointer(cb)))
	cb.editOrigWndProcPtr = win.SetWindowLongPtr(editHwnd, win.GWLP_WNDPROC, comboBoxEditWndProcPtr)

	return cb, nil
}

// NewNotifyIcon creates and returns a new NotifyIcon.
//
// The NotifyIcon is initially not visible.
func NewNotifyIcon() (*NotifyIcon, error) {
	// Create the message-only window for the NotifyIcon.
	hWnd := win.CreateWindowEx(
		0,
		syscall.StringToUTF16Ptr(notifyIconWindowClass),
		nil,
		0,
		0,
		0,
		0,
		0,
		win.HWND_MESSAGE,
		0,
		0,
		nil)
	if hWnd == 0 {
		return nil, lastError("CreateWindowEx")
	}

	// Add our notify icon to the status area and make sure it is hidden.
	nid := win.NOTIFYICONDATA{
		HWnd:             hWnd,
		UFlags:           win.NIF_MESSAGE | win.NIF_STATE,
		DwState:          win.NIS_HIDDEN,
		DwStateMask:      win.NIS_HIDDEN,
		UCallbackMessage: notifyIconMessageId,
	}
	nid.CbSize = uint32(unsafe.Sizeof(nid))

	if !win.Shell_NotifyIcon(win.NIM_ADD, &nid) {
		return nil, newError("Shell_NotifyIcon")
	}

	// We want XP-compatible message behavior.
	nid.UVersion = win.NOTIFYICON_VERSION

	if !win.Shell_NotifyIcon(win.NIM_SETVERSION, &nid) {
		return nil, newError("Shell_NotifyIcon")
	}

	// Create and initialize the NotifyIcon already.
	menu, err := NewMenu()
	if err != nil {
		return nil, err
	}

	ni := &NotifyIcon{
		id:          nid.UID,
		hWnd:        hWnd,
		contextMenu: menu,
	}

	// Set our *NotifyIcon as user data for the message window.
	win.SetWindowLongPtr(hWnd, win.GWLP_USERDATA, uintptr(unsafe.Pointer(ni)))

	return ni, nil
}

// InitWindow initializes a window.
//
// Widgets should be initialized using InitWidget instead.
func InitWindow(window, parent Window, className string, style, exStyle uint32) error {
	wb := window.AsWindowBase()
	wb.window = window
	wb.enabled = true
	wb.visible = true

	wb.name2Property = make(map[string]Property)

	var hwndParent win.HWND
	if parent != nil {
		hwndParent = parent.Handle()

		if widget, ok := window.(Widget); ok {
			if container, ok := parent.(Container); ok {
				widget.AsWidgetBase().parent = container
			}
		}
	}

	wb.hWnd = win.CreateWindowEx(
		exStyle,
		syscall.StringToUTF16Ptr(className),
		nil,
		style|win.WS_CLIPSIBLINGS,
		win.CW_USEDEFAULT,
		win.CW_USEDEFAULT,
		win.CW_USEDEFAULT,
		win.CW_USEDEFAULT,
		hwndParent,
		0,
		0,
		nil)
	if wb.hWnd == 0 {
		return lastError("CreateWindowEx")
	}

	succeeded := false
	defer func() {
		if !succeeded {
			wb.Dispose()
		}
	}()

	hwnd2WindowBase[wb.hWnd] = wb

	if !registeredWindowClasses[className] {
		// We subclass all windows of system classes.
		wb.origWndProcPtr = win.SetWindowLongPtr(wb.hWnd, win.GWLP_WNDPROC, defaultWndProcPtr)
		if wb.origWndProcPtr == 0 {
			return lastError("SetWindowLongPtr")
		}
	}

	setWindowFont(wb.hWnd, defaultFont)

	if form, ok := window.(Form); ok {
		if fb := form.AsFormBase(); fb != nil {
			if err := fb.init(form); err != nil {
				return err
			}
		}
	}

	if widget, ok := window.(Widget); ok {
		if wb := widget.AsWidgetBase(); wb != nil {
			if err := wb.init(widget); err != nil {
				return err
			}
		}
	}

	wb.enabledProperty = NewBoolProperty(
		func() bool {
			return wb.window.Enabled()
		},
		func(b bool) error {
			wb.window.SetEnabled(b)
			return nil
		},
		wb.enabledChangedPublisher.Event())

	wb.visibleProperty = NewBoolProperty(
		func() bool {
			return window.Visible()
		},
		func(b bool) error {
			wb.window.SetVisible(b)
			return nil
		},
		wb.visibleChangedPublisher.Event())

	wb.MustRegisterProperty("Enabled", wb.enabledProperty)
	wb.MustRegisterProperty("Visible", wb.visibleProperty)

	succeeded = true

	return nil
//.........这里部分代码省略.........

//.........这里部分代码省略.........
			return window.WndProc(hwnd, msg, wParam, lParam)
		}

	case win.WM_LBUTTONDOWN, win.WM_MBUTTONDOWN, win.WM_RBUTTONDOWN:
		if msg == win.WM_LBUTTONDOWN && wb.origWndProcPtr == 0 {
			// Only call SetCapture if this is no subclassed control.
			// (Otherwise e.g. WM_COMMAND(BN_CLICKED) would no longer
			// be generated for PushButton.)
			win.SetCapture(wb.hWnd)
		}
		wb.publishMouseEvent(&wb.mouseDownPublisher, wParam, lParam)

	case win.WM_LBUTTONUP, win.WM_MBUTTONUP, win.WM_RBUTTONUP:
		if msg == win.WM_LBUTTONUP && wb.origWndProcPtr == 0 {
			// See WM_LBUTTONDOWN for why we require origWndProcPtr == 0 here.
			if !win.ReleaseCapture() {
				lastError("ReleaseCapture")
			}
		}
		wb.publishMouseEvent(&wb.mouseUpPublisher, wParam, lParam)

	case win.WM_MOUSEMOVE:
		wb.publishMouseEvent(&wb.mouseMovePublisher, wParam, lParam)

	case win.WM_MOUSEWHEEL:
		wb.publishMouseWheelEvent(&wb.mouseWheelPublisher, wParam, lParam)

	case win.WM_SETFOCUS, win.WM_KILLFOCUS:
		wb.focusedChangedPublisher.Publish()

	case win.WM_SETCURSOR:
		if wb.cursor != nil {
			win.SetCursor(wb.cursor.handle())
			return 0
		}

	case win.WM_CONTEXTMENU:
		sourceWindow := windowFromHandle(win.HWND(wParam))
		if sourceWindow == nil {
			break
		}

		x := win.GET_X_LPARAM(lParam)
		y := win.GET_Y_LPARAM(lParam)

		contextMenu := sourceWindow.ContextMenu()

		var handle win.HWND
		if widget, ok := sourceWindow.(Widget); ok {
			handle = ancestor(widget).Handle()
		} else {
			handle = sourceWindow.Handle()
		}

		if contextMenu != nil {
			win.TrackPopupMenuEx(
				contextMenu.hMenu,
				win.TPM_NOANIMATION,
				x,
				y,
				handle,
				nil)
			return 0
		}

	case win.WM_KEYDOWN:
		wb.handleKeyDown(wParam, lParam)

	case win.WM_KEYUP:
		wb.handleKeyUp(wParam, lParam)

	case win.WM_DROPFILES:
		wb.dropFilesPublisher.Publish(win.HDROP(wParam))

	case win.WM_SIZE, win.WM_SIZING:
		wb.sizeChangedPublisher.Publish()

	case win.WM_DESTROY:
		if wb.origWndProcPtr != 0 {
			// As we subclass all windows of system classes, we prevented the
			// clean-up code in the WM_NCDESTROY handlers of some windows from
			// being called. To fix this, we restore the original window
			// procedure here.
			win.SetWindowLongPtr(wb.hWnd, win.GWLP_WNDPROC, wb.origWndProcPtr)
		}

		delete(hwnd2WindowBase, hwnd)

		wb.window.Dispose()
		wb.hWnd = 0
	}

	if window != nil {
		if wndProc := window.AsWindowBase().origWndProcPtr; wndProc != 0 {
			return win.CallWindowProc(wndProc, hwnd, msg, wParam, lParam)
		}
	}

	return win.DefWindowProc(hwnd, msg, wParam, lParam)
}