Last Updated: 31 May 2021 08:03 by ADMIN
Release LIB 2020.2.504 (05/04/2020)
Selection is not updated when using the arrow keys if the current selected item is outside the viewport.
Last Updated: 07 Apr 2021 05:41 by ADMIN
Release LIB 2021.1.412 (12/04/2021)

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: 05 Apr 2021 10:29 by ADMIN
Created by: Markus
Comments: 1
Category: TreeView
Type: Bug Report

Dear Telerik team,
We currently have a problem with the RadDragAndDropManager as we are currently in the process of converting from Silverlight to WPF.
We are also converting Telerik from version 2011.2 to the current version of Telerik WPF.
Now the following error happens:
If I drag an item and drag it over another dropable area, the DragCue element moves.
The error occurs as soon as "e.QueryResult" is set to true in the OnDropQuery function.
You just have to do that, otherwise the drop will not be evaluated.

I was able to recreate the whole thing in a new project with just a RadTreeView and a RadMap.
I just don't want to switch the RadDragAndDropManager to the DragDropManager because we have a lot of our own controls that run with the old one, but not with the new one.
I've already tried that, but the conversion effort is just too big.
Can you see why the DragCue element is acting so weird?

With best regards

Markus Kuhlemann

Last Updated: 08 Feb 2021 11:40 by ADMIN
Release LIB 2021.1.208 (2/8/2021)
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: 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;

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: 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: 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. 
Last Updated: 19 Jan 2018 05:47 by wu
with RadTreeView control,using MVVM binding,the xaml like :
AutoScrollToSelectedItem="True"  IsVirtualizing="False"
looking the attach files,Navigate by the  RadBreadcrumb(the RadBreadcrumb and the RadTreeView binding the same data source,and binding the same SelectedIem),
when expand the level4,the RadTreeView  can't bring the selected item to view,but scroll mouse to the seleced item view,then Navigate again the same postion ,it can scroll,the radtreeview can reach the selected item.
     I test the microsoft treeview,if the Virtualizing is true,it can't scroll the selected item,but set the Virtualizing  to false,it is good.
    the other question,how to set the style?the  selected item's highligh area can expand the full row,like the visual studio.
Last Updated: 04 Dec 2017 15:47 by Vladimir
When expanding all items with a horizontal scrollbar the last item is hidden by the scrollbar. As a workaround, you can set the IsVirtualizing property of the RadTreeView to True.
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