Button handlers not working in custom MessageBox class - vb.net

Question

I'm making a custom login form for a program that is invoked similar to a messagebox, returning a DialogResult to show whether the login was successful. There are three buttons, each returning a different DialogResult. (The code for actually checking the login data is not implemented yet.) However, only the Cancel button actually fires the appropriate Event, the other buttons do nothing.
Public Class LoginBox
Inherits Form
Private WithEvents btnLogin As New Button With {.Text = "Login", .Size = New Size(80, 25), .Location = New Point(230, 90), .BackColor = Color.Silver}
Private WithEvents btnCancel As New Button With {.Text = "Cancel", .Size = New Size(80, 25), .Location = New Point(230, 120), .BackColor = Color.Silver}
Private WithEvents btnReadOnly As New Button With {.Text = "Open in" & vbCrLf & "readonly" & vbCrLf & "mode", .Size = New Size(80, 55), .Location = New Point(130, 90), .BackColor = Color.Silver}
Private WithEvents tbNaam As New TextBox With {.Size = New Size(180, 20), .BackColor = Color.Silver, .Location = New Point(130, 20)}
Private WithEvents tbWachtwoord As New TextBox With {.Size = New Size(180, 20), .BackColor = Color.Silver, .Location = New Point(130, 55)}
Private lblNaam As New Label With {.Text = "Inlognaam:", .ForeColor = Color.Silver, .Location = New Point(65, 23)}
Private lblWachtwoord As New Label With {.Text = "Wachtwoord:", .ForeColor = Color.Silver, .Location = New Point(53, 58)}
Private Shared WaitForButton As New System.Threading.EventWaitHandle(False, Threading.EventResetMode.ManualReset)
Private Shared antwoord As DialogResult
Private Sub New()
Me.FormBorderStyle = FormBorderStyle.FixedDialog
ControlBox = False
Text = "Inlog IC agenda"
AcceptButton = btnLogin
CancelButton = btnCancel
Size = New Size(350, 205)
BackColor = Color.DimGray
Controls.Add(btnLogin)
Controls.Add(btnCancel)
Controls.Add(btnReadOnly)
Controls.Add(tbNaam)
Controls.Add(tbWachtwoord)
Controls.Add(lblNaam)
Controls.Add(lblWachtwoord)
End Sub
Public Overloads Shared Function Show(ByVal ShowReadOnlyButton As Boolean) As DialogResult
Dim X As New LoginBox
If Not ShowReadOnlyButton Then
X.btnReadOnly.Visible = False
X.Size = New Size(350, 180)
X.btnCancel.Location = New Point(130, 90)
End If
X.CenterToParent()
X.ShowDialog()
WaitForButton.WaitOne()
Return antwoord
End Function
Private Sub btnLogin_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnLogin.Click
'TODO: check login data, if incorrect, show error message
antwoord = DialogResult.OK
WaitForButton.Set()
End Sub
Private Sub btnCancel_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnCancel.Click
antwoord = DialogResult.Cancel
WaitForButton.Set()
End Sub
Private Sub btnReadOnly_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnReadOnly.Click
antwoord = DialogResult.Ignore
WaitForButton.Set()
End Sub
End Class
Testing shows the Cancel button working as expected. The other two buttons fail to raise the appropriate event, even though (in my eyes) they are coded in exactly the same way.

Answer 1

Button handlers are working, but the form is not closed. The reason is that you miss a line in event handlers.
DialogResult = antwoord
So, your event handlers should look similar like shown in the code below.
Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
'TODO: check login data, if incorrect, show error message
antwoord = DialogResult.OK
DialogResult = antwoord
WaitForButton.Set()
End Sub
Private Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click
antwoord = DialogResult.Cancel
DialogResult = antwoord
WaitForButton.Set()
End Sub
Private Sub btnReadOnly_Click(sender As Object, e As EventArgs) Handles btnReadOnly.Click
antwoord = DialogResult.Ignore
DialogResult = antwoord
WaitForButton.Set()
End Sub
"Cancel" is treated like DialogResult.None, so you had an impression that "Cancel" only works correctly.