Jim,

Sorry I didn't reply earlier ... it seems you've wasted a lot of time. What you want to do is possible. Here's code that we have in our NumericTextBox class that has the exact behavior you're looking for.

This has been subclassed from our own TextBox subclass, but I think it has everything in it that does the numeric checking and our TextBox subclass is not needed. I don't know for sure though, so test this out just sub-classing from the .NET textbox and if it still doesn't do it correctly, let me know and I can post the code for our TextBox class.

	public class MyNumericTextBox : System.Windows.Forms.TextBox
	{
		#region Declarations
		private int m_DecimalPlaces = 0;
		private decimal m_Maximum = 100;
		private decimal m_Minimum = 0;
		protected char[] AllowedChars = {'1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-'};
		protected string m_FormatString = "##0";
		#endregion

		#region Constructor
		public MyNumericTextBox ()
		{
			this.MaxLength = 3;
			this.TextAlign = System.Windows.Forms.HorizontalAlignment.Right;
		}
		#endregion

		#region Methods
		public void SetText(object val)
		{
			if (this.m_Minimum > 0)
			{
				if (val is Decimal)
					this.Text = ((decimal)val).ToString(this.m_FormatString);
			}
			else
			{
				if (val is int)
					this.Text = ((int)val).ToString(this.m_FormatString);
			}
		}
		#endregion

		#region Events
		protected override void FormatHandler(object sender, ConvertEventArgs e)
		{
			if (e.Value == System.DBNull.Value)
				e.Value = (int)0;

			if (e.Value is Decimal && e.DesiredType == typeof(string))
				e.Value = ((decimal)e.Value).ToString(this.m_FormatString);
			else if (e.Value is int && e.DesiredType == typeof(string))
				e.Value = ((int)e.Value).ToString(this.m_FormatString);
		}
		protected override void ParseHandler(object sender, ConvertEventArgs e)
		{
			if (((string)e.Value).Trim().Length == 0)
				e.Value = "0";

			if (e.DesiredType == typeof(decimal))
				e.Value = Decimal.Parse((string)e.Value, System.Globalization.NumberStyles.Any);
			else if (e.DesiredType == typeof(int))
			{
				string[] s = ((string)e.Value).Trim().Split('.');
				e.Value = Decimal.Parse(s[0], System.Globalization.NumberStyles.Any);
			}
		}
		protected override void KeyPressHandler(object sender, KeyPressEventArgs e)
		{
			// Prevent illegal characters
			bool allowed = false;
			for (int i = 0; i < this.AllowedChars.Length; i++) 
			{
				if (e.KeyChar == this.AllowedChars[i])
				{
					allowed = true;
					break;
				}
			}

			// Prevent duplicates of decimal point and minus sign
			if (allowed == false)
				e.Handled = true;
			else if ((e.KeyChar == '.' || e.KeyChar == '-') && this.Text.IndexOf(e.KeyChar) >= 0)
				e.Handled = true;

			// Prevent too many digits on either side of decimal point
			if (this.m_DecimalPlaces > 0)
			{
			}
		}
		protected override void ValidatingHandler(object sender, CancelEventArgs e)
		{
			if (this.Text.Trim().Length == 0)
				return;

			try
			{
				decimal test = Decimal.Parse(this.Text);
				if (test > this.m_Maximum || test < this.m_Minimum)
				{
					string message = "The value for this field must be between " +
						this.m_Maximum.ToString() + " and " + this.m_Minimum.ToString() + "!";
					string caption = "Value out of range";
					MessageBox.Show(message, caption, MessageBoxButtons.OK, MessageBoxIcon.Error);

					e.Cancel = true;
				}
			}
			catch (Exception ex)
			{
				System.Diagnostics.Debug.WriteLine(ex.Message);
			}
		}
		#endregion

		#region Properties
		[Description("The number of digits to display after the decimal.")]
		[DefaultValue(0)]
		public int DecimalPlaces
		{
			get {return this.m_DecimalPlaces;}
			set
			{
				this.m_DecimalPlaces = value;

				// Create the AllowedChars array for the KeyPress event handler
				if (value > 0 && this.m_Minimum < 0)
					this.AllowedChars = new char[] {(char)Keys.Back, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '.', '-'};
				else if (value > 0)
					this.AllowedChars = new char[] {(char)Keys.Back, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '.'};
				else if (this.m_Minimum < 0)
					this.AllowedChars = new char[] {(char)Keys.Back, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-'};
				else
					this.AllowedChars = new char[] {(char)Keys.Back, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0'};

				// Create the FormatString property value
				string[] format = this.m_FormatString.Split(new char[] {'.'}, 2);
				if (value > 0)
				{
					string s = new string('0', value);
					this.m_FormatString = format[0] + "." + s;
				}
				else
					this.m_FormatString = format[0];

				this.MaxLength = this.m_FormatString.Length;
				if (this.m_Minimum < 0 && this.m_Minimum.ToString().Length > this.m_Maximum.ToString().Length)
					this.MaxLength++;
			}
		}
		[Description("The maximum value allowed in the field.")]
		[DefaultValue(100)]
		public decimal Maximum
		{
			get {return this.m_Maximum;}
			set
			{
				if (value < this.m_Minimum)
					return;

				this.m_Maximum = value;

				// Create the first half of the FormatString property
				this.MaxLength = value.ToString().Length;
				int max = this.m_Minimum.ToString().Length;
				if (this.m_Minimum < 0 && max > this.MaxLength)
					this.MaxLength = max;

				if (this.MaxLength > 2 && value.ToString().Length < this.m_Minimum.ToString().Length)
					this.m_FormatString = new string('#', this.MaxLength - 2) + "0";
				else if (this.MaxLength > 1)
					this.m_FormatString = new string('#', this.MaxLength - 1) + "0";
				else
					this.m_FormatString = "0";

//				if (this.m_Minimum < 0)
//					this.m_FormatString = "-" + this.m_FormatString;

				// Finally, create the formatting
				this.DecimalPlaces = this.m_DecimalPlaces;
			}
		}
		[Description("The minimum value allowed in the field.")]
		[DefaultValue(0)]
		public decimal Minimum
		{
			get {return this.m_Minimum;}
			set
			{
				if (value > this.m_Maximum)
					return;
				
				this.m_Minimum = value;
				this.Maximum = this.m_Maximum;
			}
		}
//		[Description("The string to use with ToString to format.")]
//		[DefaultValue("##0")]
//		public string FormatString
//		{
//			get {return this.m_FormatString;}
//			set {this.m_FormatString = value;}
//		}
		#endregion
	}

~~Bonnie