Why is the TreeViewItem's MouseDoubleClick event being raised multiple times per double click?
mouseevent, treeview, treeviewitem, wpf
Solution
I know this is an old question, but as I came across it in my searches for the solution, here are my findings for any future visitors!
`TreeViewItem`s are recursively contained within each other. `TreeViewItem` is a `HeaderedContentControl` (see msdn), with the child nodes as the `Content`. So, each `TreeViewItem`'s bounds include all of its child items. This can be verified using the excellent WPF Inspector by selecting a `TreeViewItem` in the visual tree, which will highlights the bounds of the `TreeViewItem`.
In the OP's example, the `MouseDoubleClick` event is registered on each `TreeViewItem` using the style. Therefore, the event will be raised for the `TreeViewItem`s that you double-clicked on - and each of its parent items - separately. This can be verified in your debugger by putting a breakpoint in your double-click event handler and putting a watch on the event args' Source property - you will notice that it changes each time the event handler is called. Incidentally, as can be expected, the `OriginalSource` of the event stays the same.
To counter this unexpected behaviour, checking whether the source `TreeViewItem` is selected, as suggested by Pablo in his answer, has worked the best for me.
Problem
XAML ``` <TreeView Name="GroupView" ItemsSource="{Binding Documents}"> <TreeView.ItemContainerStyle> <Style TargetType="{x:Type TreeViewItem}"> <EventSetter Event="MouseDoubleClick" Handler="OnTreeNodeDoubleClick"/> </Style> </TreeView.ItemContainerStyle> .... </TreeView> ``` Code-Behind ``` private void OnTreeNodeDoubleClick(object sender, MouseButtonEventArgs mouseEvtArgs) { Console.WriteLine("{3} MouseDoubleClick Clicks={0} ChangedButton={1} Source={2} Handled={4} ButtonState={5}", mouseEvtArgs.ClickCount, mouseEvtArgs.ChangedButton, mouseEvtArgs.OriginalSource, mouseEvtArgs.Timestamp, mouseEvtArgs.Handled, mouseEvtArgs.ButtonState); } ``` I find that for one double click, the event handler is called multiple times. I'm trying to open up a document in tab on a double-click on the corresponding tree node; so I'd need to filter out the extra calls. ``` 23479156 MouseDoubleClick Clicks=1 ChangedButton=Left Source=System.Windows.Controls.TextBlock Handled=False ButtonState=Pressed 23479156 MouseDoubleClick Clicks=1 ChangedButton=Left Source=System.Windows.Controls.TextBlock Handled=False ButtonState=Pressed ``` In my slightly-complicated app, it is being raised 4 times per double-click. On a simple repro-app, it is being raised 2 times per double click. Also all the event argument parameters are the same too, so I can't distinguish the last one of a set. Any ideas why this is the way it is?