TabControl won't dispose?

[willisgt]

Okay, now, don't do this to me.

I've got a form, onto which I place a TabControl; on the various tab pages, I place panels, labels, etc. Everything is created dynamically. When each control is created, I add the name of that control to an ArrayList on the form.

When the form closes, I read through the ArrayList, from bottom to top, and dispose of each control.

This all works very will *until* I get to the TabControl. Running within the IDE doesn't produce any errors, but compile (optimized) for the device, and the Control( name ).Dispose produced an Invalid Cast Exception error.

The error occurs when I try to dispose of the TabControl.

I also started checking the type of the control before disposal, and using Control( name, TabControl ).Dispose. Same problem.

I imagine that, instead of disposing of the tab control, I could just remove all of the tab pages and set the visible to false; but I'd rather dispose of it.

Anyone?


Gary

[agraham]

I don't see this problem I'm afraid. What error occurs when you use the qualified form of Control()?

ctrl = "tab"
Control("ctrl).Dispose
'Gets compiled buts throws a runtime Invalid Cast error


ctrl = "tab"
Control(ctrl, TabControl).Dispose
'Works fine at runtime

I also started checking the type of the control before disposal, and using Control( name, TabControl ).Dispose. Same problem.

If you are checking using ControlType then look at what it returns with a msgbox, it is not what you may think. You need to check for "TabControl.TabControl" not just "TabControl"

[Erel]

Are you using the most updated ControlsEx.dll?
http://www.basic4ppc.com/forum/official-updates/1947-controlsex-update.html

[willisgt]

I am using ControlsEX.dll version 1.0.2995.34468, created 10 March 2008 at 7:52 AM.

This is the actual code I'm using:

Sub formGeneric_Close

    c = arrayListGenericControls.Count
    
    For x = ( c - 1 ) To 0 Step -1
    
        cn = arrayListGenericControls.Item( x )
    
        If StrIndexOf( ControlType( cn ), "TabControl", 0 ) <> -1 Then

            Control( cn, TabControl ).Dispose

        Else
    
            Control( cn ).Dispose

        End If

        arrayListGenericControls.RemoveAt( x )

    Next

End Sub

(One of these days I'm going to learn to include my code in the first post of a thread.)

[agraham]

I think that you have missed the significance of this sentence I posted.

Originally Posted by agraham

If you are checking using ControlType then look at what it returns with a msgbox, it is not what you may think. You need to check for "TabControl.TabControl" not just "TabControl"

EDIT :- Actually I'm wrong. I can't immediately see why that doesn't work.

[agraham]

I slightly simplified your code for testing and it works for me. Perhaps you have something else wrong - like a case-difference with the names in the ArrayList.

Sub Form2_Close
        cn = "tab"    ' tab is the name of the TabControl
        If StrIndexOf( ControlType( cn ), "TabControl", 0 ) <> -1 Then
            Control( cn, TabControl ).Dispose
        Else    
            Control( cn ).Dispose
        End If
End Sub

[willisgt]

Andy, you get full credit for this fix...

Apparently, your suggestion of checking both type 'TabControl' and 'TabControl.TabControl' had actually fixed the problem. Thing is, I also have a scrollbar on this form. So when I tried to dispose of the scrollbar, I was producing yet another cast exception error - identical, but from a different source.

My apologies for the oversight - I should have realized that both TabControl and ScrollBar types would do this.