Here is the error:

Invalid XmlnsDeclaration occurs in assembly 'Telerik.Windows.Controls.GridView, Version=2018.3.1016.1050, Culture=neutral, PublicKeyToken=5803cfa389c90ce7'. XmlnsDeclaration references a namespace 'Telerik.Windows.Controls.MultiColumnComboBox' that is not in the assembly.

It is reproducible only in Visual Studio 2010 SP1.

When placed in a RadWindow, there is a LayoutCycle exception if the layout transform is re-applied when the content of the LCC is not visible.

Workaround: Set MinHeight to the RadWindow.

The LocalizationManager doesn't apply the ResourceKey if the Content/Text properties are defined in XAML between the opening and closing tag of the control - for example Button or a TextBlock control.

If the Telerik.Windows.Controls assembly is referenced from a local folder whilst the Telerik.Controls.Navigation.dll is referenced from the installation folder, as soon as a control from Navigation is added in a UserControl, a design-time exception is raised.
The excpetion is "Error HRESULT E_FAIL has been returned from a call to a COM component."
StackTrace:    at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.Collection_InsertValue[T](PresentationFrameworkCollection`1 collection, UInt32 index, CValue value)
   at MS.Internal.XcpImports.Collection_InsertDependencyObject[T](PresentationFrameworkCollection`1 collection, UInt32 index, DependencyObject value)
   at System.Windows.PresentationFrameworkCollection`1.InsertDependencyObject(Int32 index, DependencyObject value)
   at System.Windows.Controls.UIElementCollection.InsertInternal(Int32 index, UIElement value)

Create FileThumbnail control:
I would love to have an easy way to display the thumbnail preview of a file. The Windows Shell does it, but the pInvoke code required to make this work is excessive.
Something like this:
http://stackoverflow.com/questions/1439719/c-sharp-get-thumbnail-from-file-via-windows-api
Perhaps a "RadFileThumbnail" control?
The Windows API Code Pack for Windows 7 has something like this, but you lock yourself into Windows 7 by using it.
http://archive.msdn.microsoft.com/WindowsAPICodePack

The project configuration wizard displays a list of assemblies that we can include or exclude from the current project.
It would be much more useful if this window lists all the different controls and we select the controls we want to use. Currently, we ne

If the user clicks one of the sides of the cube, it stops spinning and displays the image/control that they clicked on.
Also, if the user clicks the non-rotating image/control, then the cube starts spinning again.

If the user doesn't click on the non-rotating image/control after a specified period of time, that the cube should start rotating again on it's own.

Add metadata driven validation support for:
- RadComboBox
- RadDateTimePicker
- RadNumericUpDown

"It would be really useful to have a RadComboBox with a RadTreeView.

The combination of RadDropDownButton with a RadTreeView seems to be an insufficient workaround:
- start-up item setup
- sync current item
- IsOpen hack in MVVM
- no validation support - which is a serious drawback
- no edit/search support"

Fix the animation of the RadWrapPanel.
As a workaround:
<telerik:RadWrapPanel >
			<i:Interaction.Behaviors>
				<ei:FluidMoveBehavior AppliesTo="Children" Duration="0:0:0.4">
					<ei:FluidMoveBehavior.EaseY>
						<CubicEase EasingMode="EaseOut"/>
					</ei:FluidMoveBehavior.EaseY>
					<ei:FluidMoveBehavior.EaseX>
						<CubicEase EasingMode="EaseOut"/>
					</ei:FluidMoveBehavior.EaseX>
				</ei:FluidMoveBehavior>
			</i:Interaction.Behaviors>
</telerik:RadWrapPanel>
Check the attached project.

Now, the only supported charts for the integration between RadPivotGrid and RadChartView are Bar, Area and Line. hope also support like pie chart ...

Use Matrix3DProjection for 3D transformation