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Editorial Team
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Asked: 2026-05-22T20:37:10+00:00

I have a situation where I need to know when an item is going

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I have a situation where I need to know when an item is going to be added/removed/modified in the collection.

I tried by inheriting BindingList in a class that will trigger these events, however the “adding” event doesn’t work. The only way I found it working is by overriding EndNew() method, however I don’t find a way to get which object is going to be added in this method (if someone has a solution for this, it’s ok too!).

So built a totally new class which inherits from same interfaces/class of BindingList and implemented everything (I didn’t inherit, however, ICancelAddNew).

I bound it through databindings to my listbox and I find out that nothing works (listchanged events neither listchanging events). How can I simulate BindingList behavior on a listbox?

Any suggestion heavily appreciated, I don’t have any other ideas for a workaround

EDIT 1:

This is my collection: http://pastie.org/1978601
And this is how I bind the collection to the ListBox

        SpellCasterManager.CurrentProfile.ButtonsMacro.ListChanged += new ListChangedEventHandler(ButtonsMacro_ListChanged);
        SpellCasterManager.CurrentProfile.ButtonsMacro.ListChanging += new Expand.ComponentModel.ListChangingEventHandler(ButtonsMacro_ListChanging);
gumpButton.DataBindings.Add("Value", SpellCasterManager.CurrentProfile.ButtonsMacro, "GumpIndex", false, DataSourceUpdateMode.OnPropertyChanged);

Actually under subscribed events there is just a MessageBox.Show(“bla”);

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1 Answer

  1. Editorial Team

    • Your collection won’t detect property changes in an existing item because it doesn’t hook into the item’s property changed events as it is added to the collection.

    • BindingList<T> does listen to PropertyChanged on your item and does fire a ListChanged event when an item is added to the BindingList and it does include the index at which is is added. Try it in a test app without WinForms.

    • Adding an existing item is not the same as AddNew(). The AddingNew event is only called when AddNew() is called and allows you to supply the new instance.

    • When WinForms is involved, things get more complicated. There is the CurrencyManager to think about and also BindingSource. If no events are firing at all then check to see if you are using the CurrencyManager/BindingSource you think you are.

    • I don’t think anything in the framework uses INotifyPropertyChanging, only the original INotifyPropertyChanged. You might want to use Reflector on BindingList to see how the hooking is done and then try to incorporate INotifyPropertyChanging if your item supports it.

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