Vb.net Winforms MDI multiple instance of form open

Question

I want to know that how open multiple form in MDI parent form without duplicate same instances? For example: License Form and User Form open at the same time without duplicate.

       For Each f As Form In Application.OpenForms
            If f.Name = "License" Then
                FormOpen = True
                f.Focus()
                Return
            End If

            If f.Name = "User" Then
                FormOpen = True
                f.Focus()
                Return
            End If
        Next

        If FormOpen = False Then
            If e.Node.Name = "License" Then
                Dim license As New License
                license.MdiParent = Me
                license.Show()
            End If


            If e.Node.Name = "User" Then
                Dim license As New User
                license.MdiParent = Me
                license.Show()
            End If
        End If

Here is my code, but it only can open either one form at the same time. Anyone can help?

Answer 1

You can declare a public boolean variable in a module to avoid duplicates every time you open your forms. If you succeed opening the forms that variable stores the "True" value; if don't it stores false. You also have to store "False" to the variable in the Closed event of each form.

Below it is the source code:

Private Sub MDIParent1_Load(sender As Object, e As EventArgs) Handles MyBase.Load User.MdiParent = Me License.MdiParent = Me End Sub

Private Sub OpenLicenseAndUserFormsToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles OpenLicenseAndUserFormsToolStripMenuItem.Click
    If bool = True Then
        Exit Sub
    End If
    Try
        For Each f As Form In Me.MdiChildren
            If f.Name = "License" Then
                Dim frm As New License()
                frm.MdiParent = Me
                frm.Show()

            End If

            If f.Name = "User" Then
                Dim frm As New User()
                frm.MdiParent = Me
                frm.Show()

            End If
            bool = True
        Next
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try

End Sub