VB.Net/GUI/Error Provider

Use ErrorProvider

Imports System
Imports System.Data
Imports System.Windows.Forms
Imports System.Drawing
Public Class MainClass
    
    Shared Sub Main()
        Dim form1 As Form = New Form1
        Application.Run(form1)
    End Sub
End Class
Public Class Form1
    Private Sub txtZip_Validating(ByVal sender As Object, _
     ByVal e As System.ruponentModel.CancelEventArgs) Handles txtZip.Validating
        If Not (txtZip.Text Like "#####") Then
            ErrorProvider1.SetError(txtZip, "Invalid ZIP code format")
        Else
            ErrorProvider1.SetError(txtZip, "")
        End If
    End Sub
End Class

<Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form
    "Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub
    "Required by the Windows Form Designer
    Private components As System.ruponentModel.IContainer
    "NOTE: The following procedure is required by the Windows Form Designer
    "It can be modified using the Windows Form Designer.  
    "Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.ruponents = New System.ruponentModel.Container
        Me.txtState = New System.Windows.Forms.TextBox
        Me.txtZip = New System.Windows.Forms.TextBox
        Me.ErrorProvider1 = New System.Windows.Forms.ErrorProvider(Me.ruponents)
        CType(Me.ErrorProvider1, System.ruponentModel.ISupportInitialize).BeginInit()
        Me.SuspendLayout()
        "
        "txtState
        "
        Me.txtState.Location = New System.Drawing.Point(88, 104)
        Me.txtState.Name = "txtState"
        Me.txtState.Size = New System.Drawing.Size(40, 20)
        Me.txtState.TabIndex = 9
        "
        "txtZip
        "
        Me.txtZip.Location = New System.Drawing.Point(192, 104)
        Me.txtZip.Name = "txtZip"
        Me.txtZip.Size = New System.Drawing.Size(40, 20)
        Me.txtZip.TabIndex = 11
        "
        "ErrorProvider1
        "
        Me.ErrorProvider1.ContainerControl = Me
        "
        "Form1
        "
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(292, 130)
        Me.Controls.Add(Me.txtZip)
        Me.Controls.Add(Me.txtState)
        Me.Name = "Form1"
        Me.Text = "UseErrorProvider"
        CType(Me.ErrorProvider1, System.ruponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)
        Me.PerformLayout()
    End Sub
    Friend WithEvents txtZip As System.Windows.Forms.TextBox
    Friend WithEvents txtState As System.Windows.Forms.TextBox
    Friend WithEvents ErrorProvider1 As System.Windows.Forms.ErrorProvider
End Class