If item is expanded from the UI and viewport is scrolled to the top calling BringIndexIntoView causes the viewport to lock while scrolling.

Available in LIB version: 2016.2.516 

TreeView is in TabItem of TabControl with IsContentPreserved = False. On ContextMenu open and when working with Contextmenu, the underlying RadTreeViewItem is in MouseOverState. Changing tabs then back to the tab with the TreeView. When working with contextmenu, the underlying treeviewitem is not is mouseoverstate. Could be reproduced in CustomContextMenu QSF sample. Not reproducible in AddRemoveDisable sample.
The workaround is to set IsContentPreserved to true on the RadTabControl.

Setting the IsChecked via binding causes synchronization issue with CheckState during initial container creation.

Declined.

IsChecked and CheckState are not supported in binding scenarios. In databinding scenarios use the approach described here.
http://www.telerik.com/help/wpf/radtreeview-howto-tri-state-mvvm.html

If RadTreeView.IsEnabled  false (or the tree is inside busy BusyIndicator), then ExpandItemByPath(or GetItemByPath) does not work.

Available in LIB version: 2016.2.525

The TreeViewPanel doesn't display the TreeViewItems when the TreeView ItemsPresenter ControlTemplate element is wrapped in a Border or Grid control.

Declined.

Changing the default control template of our controls is risky, every template part has its purpose and usually it is used in code behind. 
We cannot support such template changes to not reflect the main features such as virtualization,scrolling, fast performance.

Ability to have both static and bound RadTreeViewItems or different hierarchy levels.

Reason for decline: There is no proper way this to be implemented.
 This would require huge refactoring of the DragDrop, Styling, Editing, Virtualization logic. 
Complexity of such task  is close to writing a new control from scratch.

In databinding scenarios, the Header is somehow not stretched when setting the HeaderContentAlignment to true

TreeView: PreviewUnchecked doesn't stop unchecking of parent node when handled

If we have a TreeView with its "IsTriStateMode" property set to "True" and handle PreviewUnchecked event it is still possible to "uncheck" a root node.
The root node should have at least 2 successors and only one of them is checked. And the parent node is in "intermediate" (not checked/not unchecked) state. If we handle PreviewUncheck event, clicking of the parent node result in clearing (unchecking) of this node and all successors. This should not happen.
There is a sample project attached.

The XAML team has recently reviewed this issue and will not be addressing it as at this time the team is focusing on the bugs impacting the highest number of developers. If you have encountered this issue and it is blocking for your work please contact us through the support ticketing system with details on your setup and a reference to this item.

In DataBound trees you can use the following approach =>  http://docs.telerik.com/devtools/wpf/controls/radtreeview/how-to/howto-tri-state-mvvm.html 

Dynamic change of the DataContext does not reflect the DataContext of the TreeViewItems.

The XAML team has recently reviewed this issue and will not be addressing it as at this time the team is focusing on the bugs impacting the highest number of developers. If you have encountered this issue and it is blocking for your work please contact us through the support ticketing system with details on your setup and a reference to this item.

DataTriggers that apply DefaultImageSrc, ExpandedImageSrc don't work when the TreeView is virtualized.
Reason for deletion:
The workaround is easy - just bind the DefaultImageSrc, ExpandedImageSrc to string properties from the ViewModel.
Also, a possible fix would slow down the virtualization process in the RadTreeView.

If the TreeView SelectionMode is Extended, dragging a single selected item while holding the Ctrl key will deselect the item

Available in Q1 2015

Improve the synchronization between the TreeView.IsOptionElementsEnabled with the TreeViewItem.OptionType property. In a scenario where the TreeViewItem.OptionType property is databound, changing the TreeView.IsOptionElementsEnabled property doesn't respect the databound values of the TreeViewItem.OptionType.
===
Reason for deletion: These  proeprties are marked obsolete.

When TreeView is placed inside floating VS ToolWindow and item is selected the visual state remains unchanged after focus leaves the TreeView.

Reordering checked items using the drag/drop implementation in a TreeView with IsTriStateMode=False, sets the parent item in an indetereminate state

The CheckBox`s CheckMark is mirrored when the RightToleft FlowDirecttion is set in the RadTreeView

Adding a Checked RadTreeViewItem from code behind checks its parent which is xaml defined.
On loaded event of The RadTreeView adding a parent item and checked child item with Dispatcher.beginInvoke checks the parent.

The XAML team has recently reviewed this issue and will not be addressing it as at this time the team is focusing on the bugs impacting the highest number of developers. If you have encountered this issue and it is blocking for your work please contact us through the support ticketing system with details on your setup and a reference to this item.

When the RadTreeView is virtualizaed, the images are  not shown. This works when the tree is bound to collection of objects and the DefaultImageSource is bound.

Reason for deletion:
The workaround is easy - just bind the DefaultImageSrc, ExpandedImageSrc to string properties from the ViewModel.
Also, a possible fix would slow down the virtualization process in the RadTreeView.

Items are lost after reexpanding when TreeView is Virutalized and items are set in XAML.
Currently the TreeView does not support virtualization when using XAML items.

Reason for Decline: Virtualization is not supported in non-databound treeviews.

When two equal objects are used in the source collection, the first is always selected when you try to select the others.

Workaround when TreeView is not databound.

Instead of adding objects directly in the TreeView's Items Collection, add RadTreeViewItems.
For Example, instead of
 treeView.Items.Add(1), 
treeView.Items.Add(2)

do

 treeView.Items.Add(new RadTreeViewItem(){Header = 1}, 
 treeView.Items.Add(new RadTreeViewItem(){Header = 2}

Workaround when TreeView is databound.

For example , if we databind the treeview to collection of DataItems and some dataitem is located in multiple places in the source collection.
Solution => Wrap the DataItem class in new class - DataItemWrapper. It can hold the underlying DataItem, add additional property  (for exampel ID) and override the Equals and GetHashCode methods.
This way different DataItemWrapper objects can hold equal DataItem objects. In such way if you bind the treeview to collection of DataItemWrappers the selection will be successful.

DECLINED:
The XAML team recently reviewed this bug  and won't be adressing it in future. It can be actually considered as feature request because selection should have notion for selected containers.
Unfortunately, the initial code design of the RadTreeView does not have such notion and the complexity of adding such feature now is very big.

Create localization resources for the DropActionText in the TreeViewDragVisual element. The localization resources should work as the TextDropAfter, TextDropBefore, TextDropIn and TextDropRoot properties used to work in the Legacy mode of the RadTreeView DragDrop.