Public Class WForm
Public Shared Sub ShowForm(Of FormType As {Windows.Forms.Form, New})(frmMDI As Form)
For Each ChildForm As Form In frmMDI.MdiChildren
If TypeOf ChildForm Is FormType Then
ChildForm.Focus()
Exit Sub
End If
Next
Dim frm As New FormType
frm.MdiParent = frmMDI
frm.Show()
End Sub
End Class