Events

Load Event

Occurs immediately after the Show or ShowDialog methods
Occurs just before the form is actually displayed.
If you hide and show the form again, this event is not fired
Never add or change the code in the Designer.vb file
This event can be automatically added by double clicking anywhere on the windows form while working in Design mode.

public partial class Form1 : System.Windows.Forms.Form 
{ 
  private void Form1_Load(object sender, EventArgs e) 
  { 
    this.Text = "Form Title"; 
  } 
} 

FormClosing Event

This event occurs as a form is being closed.
The behaviour of this event is different depending on whether you have a modal or modeless windows form.
You can cancel this event to prevent the form closing by setting the Cancel property to True

FormClosing Event

Run code if user exits using the X

Private m_sCurrentValues As String 
Private m_bCancelButtonPressed As Boolean 
Private m_bFormLoadComplete As Boolean 

Private Sub WindowsForm_FormClosing(ByVal sender As Object, _ 
                        ByVal e As System.Windows.Forms.FormClosing.EventArgs) _ 
                        Handles Me.FormClosing 

Dim objresult As System.Windows.Forms.DialogResult 
Dim slatestvalues As String 

   Call Tracer_AddSubroutineStart(System.Reflection.MethodBase.GetCurrentMethod) 

   If My.Settings.ERROR_OCCURRED = True Then 
      'Just exit, don't save any changes
      Exit Sub 
   End If 

   slatestvalues = Me.GetValues_Latest 
   If (m_sCurrentValues = sLatestValues) Or (m_bFormLoadComplete = False) Then 

      Call Form_Close() 
      Me.Dispose() 
      Exit Sub 

   Else 

      If (m_bCancelButtonPressed = True) Then 
         If (gSettingsFile.AreYouSureYouWantToCancel = True) Then 
            objresult = modQuestions.WindowsForm_ClosingQuestionCancelConfirmation(m_sFORMTITLE) 
         Else 
            objresult = Windows.Forms.DialogResult.Yes 
         End If 
          
         If (objresult = Windows.Forms.DialogResult.Yes) Then 
            Call Form_Close() 
            Me.Dispose() 
            Exit Sub 
         End If 
         If (objresult = Windows.Forms.DialogResult.No) Then 
            e.Cancel = True 
            Exit Sub 
         End If 

      Else 'cross in the corner has been used  
         objresult = modQuestions.WindowsForm_ClosingQuestionSaveChangesPrompt(m_sFORMTITLE) 

         If (objresult = Windows.Forms.DialogResult.Cancel) Then 
            e.Cancel = True 
            Exit Sub 
         End If 
         If (objresult = Windows.Forms.DialogResult.Yes) Then 
            If (Form_Save() = False) Then 
               e.Cancel = True 
               Exit Sub 
            End If 
            Call Form_Close() 
            Me.Dispose() 
            Exit Sub 
         End If 
         If (objresult = Windows.Forms.DialogResult.No) Then 
            Call Form_Close() 
            Me.Dispose() 
            Exit Sub 
         End If 
      End If 
   End If 

End Sub 

Private Sub btnCancel_Click(ByVal sender As System.Object, _ 
                       ByVal e As System.EventArgs) _ 
                       Handles btnCancel.Click 

   Call Tracer_AddSubroutineStart(System.Reflection.MethodBase.GetCurrentMethod) 

   m_bCancelButtonPressed = True 
   Me.Close() 

End Sub 

If (e.CloseReason = CloseReason.UserClosing) Then 
End If 

Activated Event

Disposed Event

Shown Event

Used when loading lengthy data

Windows.Forms.Application.DoEvents

Async Web Services

Using Async Web Services behind a Form

If a call has been made it is possible that the windows form might have been closed before the result has been returned
At the top of all your _Callback subroutines you need to add the following line:

If (Me.Disposed = True) Then Exit Sub 

You must also make sure the form is disposed before it is closed

Private Sub Form_Close() 
   Me.Dispose() 
   Me.Close() 
End Sub