[Lazarus] Filling ListBox without triggering OnSelectionChange

[A. Fortuny]

Le 7/01/2015 07:49, Marc Santhoff a écrit :
> Hi,
>
> it has been a very long time since I've programmed GUIs. I have
> forgotten how to fill a ListBox without having the event handler
> OnSelectionChange executed.
I've had the same problem for years, until I "invented" my method:
- fill in the two events OnEnter and OnExit for the control
- generate the code for the OnSelectionChange event and drop immediately 
the event in the component explorer
- manually fill in the following code in the three envents:

TMyForm.MyComponentEnter(Sender: TObject);
begin
   MyComponent.OnSelectionChange := MyComponentSelectionChange;
// do the same for all other events you want to drive
end

TMyForm.MyComponentSlectionChange(Sender: TObject; ...);
begin
   // do whatver to do when the event fires
end

TMyForm.MyComponentExit(Sender: TObject);
begin
   MyComponent.OnSelectionChange := nil
end

Of course you can control any firing event using the OnEnter and OnExit 
events of the control. This allows the program to fire events only when 
the user enters the control.
I think that GUI's  lack a control property wich indicates whether the 
events should always fire or fire only when the user enters the control.

Antonio.
>
> I have tried (Un)LockSelectionChange on the list, setting ItemIndex to
> -1, all in the forms create method. I've tried using add() or assign()
> on the listbox's Items, nothing helps.
>
> The wiki on TListBox doesn't say anything on this topic, neither does
> the LCL help document.
>
> How can it be done?
>



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