[tariq2812]

كود :

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        For Each f As Form In My.Application.OpenForms

            If f.Name = "frm_InvFrm" Then

                Exit Sub
            End If

        Next




        Dim frm_InvFrm_new As New frm_InvFrm
        frm_InvFrm_new.Name = "frm_InvFrm"
        frm_InvFrm_new.Show()
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        Dim n As Integer = 0
        For Each f As Form In My.Application.OpenForms

            If f.Name = "frm_InvFrm" Then

                n += 1
            End If

            If n > 4 Then
                Exit Sub
            End If

        Next




        Dim frm_InvFrm_new As New frm_InvFrm
        frm_InvFrm_new.Name = "frm_InvFrm"
        frm_InvFrm_new.Show()
    End Sub