Show "Wait ..." message when extending TreeView in WPF

Question

I have many elements in my TreeView, and the elements are also very complex. I do not want to use virtualization. The TreeView extension sometimes takes a lot of time. So, is there some kind of event like "IsTreeViewExpanding" or something like that, where I can show information like "TreeView is generated ... Please wait". How can I achieve something like this?

Answer 1

Since WPF TreeView does not have a BeforeExpand event, you seem to need to hack the method OnExpanded()in TreeViewItem, as described in this MSDN forum post .