Last Updated: 24 Aug 2020 10:56 by ADMIN
Release LIB 2020.2.824
The children of an expanded RadTreeViewItem dropped inside another item are not indented correctly. 
Last Updated: 26 May 2020 08:34 by ADMIN
Release LIB 2020.2.525 (5/26/2020)

Select nested item in virtualized treeview with single selection mode.

Collapse its parent. Select item in the level of the parent. Expand the parent and notice two items are visually selected.

Expexted : only the last selected item with mouse should be visually selected.


private void TreeView_ItemPrepared(object sender, RadTreeViewItemPreparedEventArgs e)
    if ((e.PreparedItem.IsSelected == true && this.TreeView.SelectedItem != null && this.TreeView.SelectedItem != e.PreparedItem.Item))
        e.PreparedItem.IsSelected = false;
Last Updated: 14 May 2020 07:23 by ADMIN

TreeView is in dropdowncontent of a DropDownButton. BringPathIntoView is called on loaded of the button (or the tree). It tries to bring several nested levels deep for example item (4 levels deep).
On opening the button , the scrollviewer is not scrolled to the desired item.

Posssible workarounds:

 - invoke the BringPathIntoView method in a Dispatcher.BeginInvoke call

 - disable the treeview animations before the call and enable them after the call ( telerik:AnimationManager.IsAnimationEnabled = False)

Last Updated: 08 Apr 2020 06:59 by ADMIN


I found a bug when drag&dropping selected tree nodes (extended multi-selection) when the tree is virtualized. Items that never got into view are missing from the Payload Manager Data object. If virtualization is off, works as expected.

Please see modified sample for demonstration. I added 200+ items to League A -> Division A. Select the first item, quickly scroll by dragging vertical scrollbar to the bottom of the list and extend selection to the whole list. Then perform drag and drop. Note, not all items were moved.

Also, the drag visual helper moves and updates very very slowly when dragging hundredths of objects. In our application, we have thousands of objects, which makes it unusable


Thank you for a quick fix.


Last Updated: 31 Mar 2020 11:15 by ADMIN
SelectedItems collection not updated when items are removed
Last Updated: 20 Feb 2020 13:40 by ADMIN
Release R1 2020 SP
Virtualized TreeView is bound to collection of models and IsSelected of RadTreeViewItem is 2way bound to IsSelected of model.
Select the 10th item with mouse. 
Reset the items of the tree to a subset (1-15) containing the selected item.
Select the 5th item with mouse and shift key down.
Expected: Range 5-10 of items is selected.
Actual: Range 10-15 of items is selected.

Last Updated: 18 Feb 2020 08:28 by ADMIN
Release R1 2020 SP
When switching to a different window, the selected item in the RadTreeView stays in a selected in-focus state. The expected behavior is not to be focused any more (turn gray).
Last Updated: 10 Feb 2020 09:36 by ADMIN
Release LIB 2020.1.210 (2/10/2020)
Selecting an item via tap does not work when ScrollViewer.PanningMode has a value other than None.
Last Updated: 04 Feb 2020 12:26 by ADMIN
Currently when the UI Virtualization is enabled, the RadTreeView sets the IsExpanded property of the RadTreeViewItems to False when they don't have any children. We can add a mechanism by which this can be stopped. 
Last Updated: 17 Jan 2020 09:16 by ADMIN

When a large number of items are selected through extended selection (with a lot of items on the first level of the RadTreeView) the selection does not work correctly. 

Workaround - make the selection in viewmodels manually and provide 2way bindings in style
                <Style TargetType="telerik:RadTreeViewItem">
                    <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
                    <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
private void SomeRadTreeView_SelectionChanged(object sender, SelectionChangedEventArgs e)
            int count = e.AddedItems.Count;
            if (count > 1)
                SomeViewModel first = e.AddedItems[0] as SomeViewModel;
                SomeViewModel last = e.AddedItems[count - 1] as SomeViewModel;
                this.SomeRadTreeView.SelectionChanged -= this.SomeRadTreeView_SelectionChanged;
                this.SomeRadTreeView.AutoScrollToSelectedItem = false;
                this.ViewModel.SelectRange(first, last);
                this.SomeRadTreeView.AutoScrollToSelectedItem = true;
                this.SomeRadTreeView.SelectionChanged += this.SomeRadTreeView_SelectionChanged;

Last Updated: 08 Jan 2020 09:52 by ADMIN
Selection is not updated when using the arrow keys if the current selected item is outside the viewport.
Last Updated: 17 Jul 2019 11:31 by ADMIN

Select an item with mouse, scroll thousands of items down and then shift select item to perform range selection. This will block the UI thread for seconds. 

Last Updated: 19 Mar 2019 15:39 by ADMIN
Currently, in Extended SelectionMode,  RadTreeView selects multiple Items with Shift + Click selection only if there is another RadTreeViewItem already selected with mouse.

Other controls like RadListBox, RadGridView hold reference to the business object which should be the start (the target) of the multiselection. RadTreeView holds such reference with weak reference to the container (RadTreeViewItem) and only if this container is selected with Mouse.

Adding such method (SetSelectionAnchor) in RadTreeView will help users better control the multiselection process.
Won't Fix
Last Updated: 08 Feb 2019 15:23 by ADMIN
This behavior is reproducible when we have applied Material theme and we have disabled the selection and drag of a RadTreeViewItem. 
A possible workaround is to set the MaterialAssist.CheckedBrush attached property to Null of the RadTreeViewItem which you don't want to select and drag.


 <telerik:RadTreeViewItem Header="RootItem" material:MaterialAssist.CheckedBrush="{x:Null}" />
Last Updated: 04 Sep 2018 08:20 by ADMIN
Created by: Telerik Admin
Comments: 1
Category: TreeView
Type: Feature Request
Add a possibility to disable selection of RadTreeViewItem.
Last Updated: 22 Aug 2018 17:28 by Werner
Setting the HeaderStringFormat of RadTreeViewItem does not format the Header.

As a workaround, HeaderTemplate of RadTreeViewItem could be set which has TextBlock with StringFormat property set on its Text Binding.

 <DataTemplate x:Key="template">
                <TextBlock Text="{Binding ., StringFormat='Received ({0:N0})'}" />

Available in LIB version: 2016.3.1121
Last Updated: 30 Jul 2018 08:13 by ADMIN
When you reorder the collection very fast an exception is thrown. This is reproducible when the UI virtualization is enabled with its virtualization mode set to Recycling, and an item is selected. Also, you can observe some missing items glitches instead of the exception. To reproduce this you can call the ObservableCollection's Move() method several times in a single method (see the attached project). 

In this case also a NullReferenceException is thrown sometimes instead of the InvalidOperationException.

To work this around delay the reordering calls so that the treeview has time to properly measure and arrange itself. For example:

Items.Move(10, 2);
Application.Current.Dispatcher.BeginInvoke(new Action(() =>
Items.Move(10, 2);
}), System.Windows.Threading.DispatcherPriority.Background);
Last Updated: 27 Jun 2018 17:48 by ADMIN
Created by: Telerik Admin
Comments: 3
Category: TreeView
Type: Bug Report
System.Windows.Media.Animation Warning is apparent during DragDrop in the TreeView in WPF. 
Last Updated: 05 Apr 2018 10:34 by ADMIN
The built-in drag drop mechanism works with the containers of the items and makes a snapshot of them for the DragVisual. Thus, dragging multiple selected items that are not present in the viewport is not possible.
Last Updated: 26 Feb 2018 12:40 by ADMIN
Created by: Telerik Admin
Comments: 2
Category: TreeView
Type: Bug Report
The scroll position resets when the measure of the treeview panel is fired for some reason.

For example, when the RadTreeView is placed inside a RadPanelBarItem and the RadPanelBar's ScrollViewer is disabled, resizing the RadPanelBar resets the RadTreeView scroll position. 
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