I am using a standard TreeView in a WinForms application and everything works fine except for one issue:
Parts of the system need to change depending on the selected TreeNode, which works fine using the AfterSelect event.
However, sometimes the TreeView will get cleared completely resulting in an empty selection which does not trigger this event.
At the momemnt I am calling the event callback manually to fix this issue.
This is obviously dangerous, since I will forget to call this function somewhere. Is there a “correct” way to do this?
Thank You!
This is by design. The underlying native Windows controls only generate notifications for things you cannot figure out yourself. The ListBox control for example doesn’t have any event that tells you an item got added or removed. Which is because there is no way for the user to add or remove items. Similarly, there’s no way for the user to remove the nodes from a tree view.
These kinds of changes requires code that you write. Since it is your code, you cannot not know that these changes happened. If you want an event then you’ll have to raise it yourself. Beware that this is harder than it looks, the TreeNodeCollection class doesn’t reliably let you generate an event for programmatic changes to the node collection. It doesn’t behave like an ObservableCollection. You are definitely better off by not needing this event.