func (wb *WindowBase) setAndClearStyleBits(set, clear uint32) error {
	style := uint32(win.GetWindowLong(wb.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	if newStyle := style&^clear | set; newStyle != style {
		win.SetLastError(0)
		if win.SetWindowLong(wb.hWnd, win.GWL_STYLE, int32(newStyle)) == 0 {
			return lastError("SetWindowLong")
		}
	}

	return nil
}

func (fb *FormBase) SetOwner(value Form) error {
	fb.owner = value

	var ownerHWnd win.HWND
	if value != nil {
		ownerHWnd = value.Handle()
	}

	win.SetLastError(0)
	if 0 == win.SetWindowLong(
		fb.hWnd,
		win.GWL_HWNDPARENT,
		int32(ownerHWnd)) && win.GetLastError() != 0 {

		return lastError("SetWindowLong")
	}

	return nil
}

func (tw *TabWidget) removePage(page *TabPage) (err error) {
	page.SetVisible(false)

	style := uint32(win.GetWindowLong(page.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	style &^= win.WS_CHILD
	style |= win.WS_POPUP

	win.SetLastError(0)
	if win.SetWindowLong(page.hWnd, win.GWL_STYLE, int32(style)) == 0 {
		return lastError("SetWindowLong")
	}

	page.tabWidget = nil

	return page.SetParent(nil)
}

func (tw *TabWidget) onInsertedPage(index int, page *TabPage) (err error) {
	item := tw.tcitemFromPage(page)

	if idx := int(win.SendMessage(tw.hWndTab, win.TCM_INSERTITEM, uintptr(index), uintptr(unsafe.Pointer(item)))); idx == -1 {
		return newError("SendMessage(TCM_INSERTITEM) failed")
	}

	page.SetVisible(false)

	style := uint32(win.GetWindowLong(page.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	style |= win.WS_CHILD
	style &^= win.WS_POPUP

	win.SetLastError(0)
	if win.SetWindowLong(page.hWnd, win.GWL_STYLE, int32(style)) == 0 {
		return lastError("SetWindowLong")
	}

	if win.SetParent(page.hWnd, tw.hWnd) == 0 {
		return lastError("SetParent")
	}

	if tw.pages.Len() == 1 {
		page.SetVisible(true)
		tw.SetCurrentIndex(0)
	}

	tw.resizePages()

	page.tabWidget = tw

	page.applyFont(tw.Font())

	return
}

// SetParent sets the parent of the WidgetBase and adds the WidgetBase to the
// Children list of the Container.
func (wb *WidgetBase) SetParent(parent Container) (err error) {
	if parent == wb.parent {
		return nil
	}

	style := uint32(win.GetWindowLong(wb.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	if parent == nil {
		style &^= win.WS_CHILD
		style |= win.WS_POPUP

		if win.SetParent(wb.hWnd, 0) == 0 {
			return lastError("SetParent")
		}
		win.SetLastError(0)
		if win.SetWindowLong(wb.hWnd, win.GWL_STYLE, int32(style)) == 0 {
			return lastError("SetWindowLong")
		}
	} else {
		style |= win.WS_CHILD
		style &^= win.WS_POPUP

		win.SetLastError(0)
		if win.SetWindowLong(wb.hWnd, win.GWL_STYLE, int32(style)) == 0 {
			return lastError("SetWindowLong")
		}
		if win.SetParent(wb.hWnd, parent.Handle()) == 0 {
			return lastError("SetParent")
		}
	}

	b := wb.Bounds()

	if !win.SetWindowPos(
		wb.hWnd,
		win.HWND_BOTTOM,
		int32(b.X),
		int32(b.Y),
		int32(b.Width),
		int32(b.Height),
		win.SWP_FRAMECHANGED) {

		return lastError("SetWindowPos")
	}

	oldParent := wb.parent

	wb.parent = parent

	var oldChildren, newChildren *WidgetList
	if oldParent != nil {
		oldChildren = oldParent.Children()
	}
	if parent != nil {
		newChildren = parent.Children()
	}

	if newChildren == oldChildren {
		return nil
	}

	widget := wb.window.(Widget)

	if oldChildren != nil {
		oldChildren.Remove(widget)
	}

	if newChildren != nil && !newChildren.containsHandle(wb.hWnd) {
		newChildren.Add(widget)
	}

	return nil
}