vb.net messagebox click behaves different to enter key - vb.net

Question

net gurus
I have the following piece of code. If I mouse click on the messagebox OK button the code behaves correctly but if I press enter it sets focus back to txtusename but then jumps to txtpassword. Any ideas why?
Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click
If String.IsNullOrEmpty(txtUserName.Text) Then
Dim msgResult As DialogResult = MessageBox.Show("User Name required", "Invalid Entry", MessageBoxButtons.OK, MessageBoxIcon.Warning)
If msgResult = DialogResult.OK Then
txtUserName.Focus()
End If
Return
ElseIf String.IsNullOrEmpty(txtPassword.Text) Then
Dim msgResult As DialogResult = MessageBox.Show("Password required", "Invalid Entry", MessageBoxButtons.OK, MessageBoxIcon.Warning)
'MsgBox("Password required", vbOKOnly, vbExclamation)
txtUserName.Select()
txtPassword.Select()
Return
End If

Answer 1

In case there is a value on txtUserName and the txtPassword is null or empty you show a MessageBox. After showing the MessageBox (no matter the user selected) you select the txtUserName and txtPassword. Since you can only select one TextBox, the txtPassword is finally selected.
On the Form the txtUserName is selected first, so the cursor jumps from txtPassword to txtUserName. At the end the txtPassword is selected so the cursor jumps now from txtUserName to txtPassword.
You also using .Select on the ElseIf part. In case you want to set the cursor to the TextBox you need to use .Focus (like on the If part).
You need to remove the txtUserName.Select() on the ElseIf and using .Focus instead of .Select on txtPassword to solve your issue:
Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click
If String.IsNullOrEmpty(txtUserName.Text) Then
MessageBox.Show("User Name required", "Invalid Entry", MessageBoxButtons.OK, MessageBoxIcon.Warning)
txtUserName.Focus()
Return
ElseIf String.IsNullOrEmpty(txtPassword.Text) Then
MessageBox.Show("Password required", "Invalid Entry", MessageBoxButtons.OK, MessageBoxIcon.Warning)
txtPassword.Focus()
Return
End If
'more code for database connection.
End Sub