In this VB.Net Tutorial/Code Example I’ll be showing you how to check to see whether there is an instance of a form open in your application.
''' <summary>
''' This method deals with checking to see whether a particular form is open
''' </summary>
''' <param name="formName">The name of the form that you are looking for</param>
''' <returns></returns>
''' <remarks></remarks>
Public Shared Function isFormOpen(ByVal formName As String) As Boolean
Dim frm As Form
Dim i As Integer = 0
Dim found As Boolean = False
While i < Application.OpenForms.Count
frm = Application.OpenForms.Item(i)
If frm.Name.ToLower = formName.ToLower Then
found = True
Exit While
End If
i += 1
End While
Return found
End Function{/code}