Cannot get comboboxes working properly within a child form? VB

Question

I have spent a long time trying to find a solution for the problem I am having with comboboxes within a child form. I'm sure this must be a Microsoft error and not something I'm doing wrong... I would really appreciate some help, Thanks in advance...

The best way to explain the problem would be to tell you what I have done so far:

If you open a new Project in VB and add two Windows Forms. Form1 will be the parent. Form2 will be the child.

On Form1 add 1 x panel(Form2 will open up within the panel so make sure the panel is big enough to fit Form2) and 1 x button. The only code needed for this form is:

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

Form2.Show()

End Sub

On Form2 Add one Textbox and one combobox. Copy the following code into Form2:

Private Sub Form2_GotFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.GotFocus

    ActivateMdiChild(Me)

End Sub

Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    TopLevel = False
    Form1.Panel1.Controls.Add(Me)
    Me.BringToFront()

End Sub

Now run the program and click button1 to open form2 (form2 should now open within panel1).

The comboboxes and textboxes lose some of there functions for example: 1. You cant set focus on combobox without hitting drop-down 2. You cant highlight text properly in either the combobox or textbox. 3. You cant set the cursor index position using your mouse in the combobox or text box.

Does anyone know a way around this?? Mainly for the combobox as I've got some functions working for the textbox.

Regards, Ben

Answer 1

Your click event should probably look something like this:

Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
  Dim f As New Form2
  f.TopLevel = False
  f.Dock = DockStyle.Fill
  f.Visible = True
  Panel1.Controls.Add(f)
  f.BringToFront()
End Sub

and you can pretty much discard the code you have posted for Form2. Moving a form that is an MDI child of the parent to a child control of a panel is a bit awkward. I'm guessing that is not what you are really trying to do.

Also, this current code will just keep putting a new Form2 over any existing controls or forms that are already in the panel. Make sure to dispose of unwanted controls.

Answer 2

Another way to get the functionality you are trying to get on Form2 is to set Form1 as an MDI container through the IsMdiContainer property on Form1. You could then call Form2 in the Form1 button click with something like this:

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim f As New Form2()
    f.MdiParent = Me
    f.Show()
End Sub

This would obviously create a new instance of Form2 every time you click Button1, so you could change the click actions to Form2.Show() and in Form2 constructor set the MdiParent to Form1. That should only create one instance of Form2.

I'm curious why you're mimicking MDI functionality through the Panel?