Button.Focus

[ADO DOT NET]

I just cannot understand why it is not working?

It seems everything is alright:

   Delegate Sub SetFocusCallback(ByVal Focus As Boolean)
   Private Sub SetFocus(ByVal Focus As Boolean)
       If Me.OKButton.InvokeRequired Then
           Dim d As New SetFocusCallback(AddressOf SetFocus)
           Me.Invoke(d, New Object() {Focus})
       Else
           Me.OKButton.Focus = Focus
       End If
   End Sub
...
Me.SetFocus(True)
...

Also in this line:

Me.OKButton.Focus = Focus

I get this error:

Error 1 Expression is a value and therefore cannot be the target of an assignment.

[PlausiblyDamp]

Focus is a method not a property, try

Me.OKButton.Focus()

[ADO DOT NET]

So you mean I should change my code to something like this:

   Delegate Sub SetFocusCallback()
   Private Sub SetFocus()
       If Me.OKButton.InvokeRequired Then
           Dim d As New SetFocusCallback(AddressOf SetFocus)
           Me.Invoke(d, New Object() {Focus})
       Else
           Me.OKButton.Focus()
       End If
   End Sub
...
usage
...
Me.SetFocus()

I just am not sure if this section:

       If Me.OKButton.InvokeRequired Then
           Dim d As New SetFocusCallback(AddressOf SetFocus)
           Me.Invoke(d, New Object() {Focus})
       Else

is correct?

[ADO DOT NET]

Cross-thread operation not valid: Control 'SupportForm' accessed from a thread other than the thread it was created on.

 

for this line:

 

Me.Invoke(d, New Object() {Focus})

[ADO DOT NET]

Please, I need help:(

[snarfblam]

What is "Focus" in the line:

 

Me.Invoke(d, New Object() {Focus})

 

If it is not a declared variable then it will refer to the form's focus method, in which case you may be inadvertently invoking it, which you would be doing across threads, hence your error.

[ADO DOT NET]

So sorry for replying again!

So how should I update it?

It didn't work for me:(

[snarfblam]

Try changing:

 

____Me.Invoke(d, New Object() {Focus})

 

to either

 

____Me.Invoke(d, New Object(0) {})

 

or

 

____Me.Invoke(d, Nothing)

[ADO DOT NET]

What about:

 

Me.Invoke(d)

 

Which one do you prefer?

[MrPaul]

Me.Invoke(d)

 

Me.Invoke(d)

 

That is correct (since the delegate takes no arguments). Good luck :cool:

[ADO DOT NET]

Just wanted to thank you all for your helps, I have learned a lot from you:)

[ADO DOT NET]

Hi all,

I just have one more last question:

       If SaveCheckBox.Checked = True Then SaveButton.Enabled = True

I just wanna check if my check box on form is checked then enable a button in my safe thread.

But could not implement this.

Can someone help me? :)

[ADO DOT NET]

   Delegate Sub SetFocusCallback()
   Private Sub SetFocus()
       If Me.SaveCheckBox.InvokeRequired Then
           Dim d As New SetFocusCallback(AddressOf Enabled)
           Me.Invoke(d, New Object() {Enabled})
       Else
           If Me.SaveCheckBox.Enabled = True Then SaveButton.Enabled = True
       End If
   End Sub

It won't work! :(