Underlines of MaskedTextBox disappear - vb.net

Question

i have a problem in Windows Forms. I've created a form where I can enter the first and last name and click on the Search-Button to show another form with the following code:
Private Sub btnSearchUser_Click(sender As Object, e As EventArgs) Handles btnSearchUser.Click
If Me._clsfrmChild Is Nothing Then
Me._clsfrmChild = New clsFrmChild
End If
If Me._clsfrmChild.ShowDialog = False Then
Me._clsfrmChild.ShowDialog(Me)
End If
In the second form I have a MaskedTextbox:
Empty MaskedTextBox
Whatever I do, If I close the second form with Visible = False and reopen it again, the MaskedTextBox looks like this:
MaskedTextBox without underlines
I close the second form that way:
Private Sub btnAbort_Click(sender As Object, e As EventArgs) Handles btnAbort.Click
Me.Visible = False
End Sub
Does someone of you know why this problem is caused?

Answer 1

This is really not the way you supposed to work with dialogs. The proper way is this
dim result as DialogResult
using f as Form = New MyForm()
result = f.ShowDialog()
' here you can work with form's public properties etc
end using
' optionally here you can continue massaging the result
if result = DialogResult.Ok then
' do for ok result
else
' do for other result. You can have severul results - add elseif
end if

Answer 2

Here is how to make a dialog with results in general. This will be similar to how MessageBox.Show() works.
Public Class clsFrmChild
Private Sub New()
InitializeComponent()
End Sub
Public Shared Shadows Function Show() As DialogResult
Dim result As DialogResult
Using f As New clsFrmChild()
result = f.ShowDialog()
End Using
Return result
End Function
Private Sub OkButton_Click(sender As Object, e As EventArgs) Handles OkButton.Click
DialogResult = DialogResult.OK
Close()
End Sub
Private Sub CancelButton_Click(sender As Object, e As EventArgs) Handles CancelButton.Click
DialogResult = DialogResult.Cancel
Close()
End Sub
End Class
Note the constructor is privatized so there is no more Me._clsfrmChild = New clsFrmChild. You will see the displaying of the modal dialog is much simpler when called like MessageBox
Private Sub btnSearchUser_Click(sender As Object, e As EventArgs) Handles btnSearchUser.Click
Dim result = clsFrmChild.Show() ' static method call instead of instance method
Select Case result
Case DialogResult.OK
MessageBox.Show("Ok")
Case DialogResult.Cancel
MessageBox.Show("Cancel")
End Select
End Sub
If you are not interested in returning a standard DialogResult, you could change the return type to whatever you like such as a custom class, with more information (such as you want to return a string in addition to DialogResult) i.e.
Public Class clsFrmChildResult
Public Property Text As String
Public Property DialogResult As DialogResult
End Class
...
Public Shared Shadows Function Show() As clsFrmChildResult
Dim result As clsFrmChildResult
Using f As New clsFrmChild()
Dim dr = f.ShowDialog()
result = New clsFrmChildResult With {.Text = TextBox1.Text, .DialogResult = dr}
End Using
Return result
End Function
...
Private Sub btnSearchUser_Click(sender As Object, e As EventArgs) Handles btnSearchUser.Click
Dim result = clsFrmChild.Show()
Select Case result.DialogResult
Case DialogResult.OK
MessageBox.Show("Ok")
Dim myString = result.Text
Case DialogResult.Cancel
MessageBox.Show("Cancel")
End Select
End Sub