public class LabelEx : Label

    {

        private bool autoHeight = true;

        [DefaultValue(true)]

        public bool AutoHeight

        {

            get { return this.autoHeight; }

            set

            {

                this.autoHeight = value;

                RecalcHeight();

            }

        }

        protected override void OnAutoSizeChanged(EventArgs e)

        {

            base.OnAutoSizeChanged(e);

            RecalcHeight();

        }

        protected override void OnFontChanged(EventArgs e)

        {

            base.OnFontChanged(e);

            RecalcHeight();

        }

        protected override void OnSizeChanged(EventArgs e)

        {

            base.OnSizeChanged(e);

            RecalcHeight();

        }

        protected override void OnTextChanged(EventArgs e)

        {

            base.OnTextChanged(e);

            RecalcHeight();

        }

        private void RecalcHeight()

        {

            if (this.AutoSize || !this.autoHeight)

                return;

            var size = TextRenderer.MeasureText(this.Text, this.Font);

            int lc = (int)Math.Ceiling(size.Width * 1.0 / this.ClientSize.Width);

            this.Height = lc * size.Height;

        }

    }

    public class TextBoxEx : TextBox

    {

        private string placeHolderText;

        [DefaultValue("")]
        [Editor("System.ComponentModel.Design.MultilineStringEditor, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]

        public string PlaceHolderText

        {

            get { return this.placeHolderText; }

            set

            {

                this.placeHolderText = value;

                PaintPlaceHolderText();

            }

        }

        protected override void WndProc(ref Message m)

        {

            base.WndProc(ref m);


            //若使OnPaint()起作用，须设置this.SetStyle(ControlStyles.UserPaint,true);，但这样控件显示都得重绘，所以直截WM_PAINT消息

            //WM_PAINT消息：0xf  WM_CTLCOLOREDIT：0x133

            if (m.Msg == 0xf || m.Msg == 0x133)

                PaintPlaceHolderText();

        }

        private void PaintPlaceHolderText()

        {

            if (this.Focused || string.IsNullOrEmpty(this.placeHolderText) || !string.IsNullOrEmpty(this.Text))

                return;

            var g = Graphics.FromHwnd(this.Handle);

            var bounds = this.ClientRectangle;

            g.FillRectangle(new SolidBrush(this.BackColor), bounds);

            var sf = new StringFormat();

            switch (this.TextAlign)

            {

                case HorizontalAlignment.Left:

                    sf.Alignment = StringAlignment.Near;

                    break;

                case HorizontalAlignment.Center:

                    sf.Alignment = StringAlignment.Center;

                    break;

                case HorizontalAlignment.Right:

                    sf.Alignment = StringAlignment.Far;

                    break;

            }

            bounds.Offset(-, );

            g.DrawString(this.placeHolderText, this.Font, new SolidBrush(Color.DarkGray), bounds, sf);

        }

    }