Visual Basic

Andraw Tang wrote:

Do you think it is necessary to create a class scope reference to child form?

Andraw Tang wrote:

or just create a local referece when user click tree node, add set it as MDI child and show it? which way is better?

Andraw Tang wrote:

If we use local reference and user click tree node 1, the first child form is created and shown, how about if user click tree node 1 again?

Andraw Tang wrote:

reason I use MDI is because all these data are related together, so when user input data to a form, he can look at data in other form for reference.

frmChild1 = New frmChildForm1
AddHandler frmChild1.FormClosed, AddressOf ChildFormClosed

'more code
End Sub

Private Sub ChildFormClosed(ByVal sender as System.Object, ByVal e as System.Windows.Forms.FormClosedEventArgs)
    CType(sender, Form).Dispose
    
    If TypeOf sender Is frmChildForm1 Then
        frmChild1 = Nothing
    End If
End Sub

Private Sub TreeView1_NodeMouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeNodeMouseClickEventArgs) Handles TreeView1.NodeMouseClick

        Select Case e.Node.Text
            Case "Node0"
                Dim frm As New Form1
                frm.Name = "Form1"

                frm.MdiParent = Me
                'Following Conditions make single Instance of form1
                Dim OldForm = System.Windows.Forms.Application.OpenForms(frm.Name)
                If IsNothing(OldForm) Then

                    OldForm = frm
                End If

                If Not OldForm.Visible Then

                    frm.Show()
                Else

                    OldForm.Show()
                    OldForm.Focus()
                End If



            Case "Node1"
                'Not Single Instance. to make single instance add above code
                Dim frm As New Form2

                frm.Name = "Form2"

                frm.MdiParent = Me
                frm.Show()
            Case Else

                MsgBox("None")
        End Select

    End Sub

Michael Schäuble wrote:

the Express version doesn't have any 'Attach to process'

if isnothing(InvCode) then
    ' Doesn't exist
  InvCode = new DataGridViewComboBoxColumn()
  BsDataGRidView.Columns.Insert(5,InvCode)
  'Do anything else you want
else
  ' Already exists
  ' Do what ever you want to do with it
end if

'Or Do whatever you want to the object regardless here