The RadHtmlPlaceholder control gets misplaced when displayed inside a RadWindow in a zoomed browser. The issue can be reproduced in the HtmlPlaceholder WindowIntegration demo example.

The placeholder disappears if it's in a RadPane and you close another RadPane

When the user navigates in a page displayed in the placeholder and then it is removed and added in the visual tree (when in RadDocking for example) the original SourceUrl is displayed while ideally this should be the page that the user has navigated to.
Update: You can fix this by setting the HTMLPlaceholder's KeepContentInMemory property to True.

The fix will be available in our official release 2015 Q2. 

When Maximize and then drag -- the LayoutChangeEnded event is not invoked and LayoutChangeStarted/Ended are not invoked anymore for all actions.

When IsTabStop = False the focus is going through :

 *  RadAutoCompleteBox
 *  RadComboBox (when IsEditable is set to True)
 *  RadNumericUpDown
 *  RadMaskedTextInput
 *  RadDatePicker
 *  RadDateTimePicker

Available in the R3 2016 Release.

For RadAutoCompletebox, RadComboBox, RadDateTimePicker and RadNumericUpDown, the TabNavigationExtensions.IsTabStop attached property should be used to indicate whether the control is included in the tab navigation cycle.

For RadMaskedTextInput, MaskedInputExtensions.IsEditorTabStop attached property should be used.

When zooming in to a level so that the width of a visible timeline item becomes more than 30000 pixels, the item does not display correctly.

RadComboBox with bound ItemsSource and SelectedValue to the DataContext. When the DataContext is changed and the new DataContext ItemsSource does not contain the currently selected item, the old DataContext SelectedValue is set to null. This problem does not occur in WPF.

Place RadTransitionControl with size 200x100 inside of ViewBox with size 400x250.
Available in LIB version 2015.2.803 , it will be also available in the 2015 Q3. 

The fix will be available in our official release 2015 Q2.

When using custom DataTemplates for the timeline items, the selection feature does not work,
 
The workaround for this problem is to use a custom control in the DataTemplate that inherits TimelineItemControlBase. You can use the ControlTemplate of this custom control to define the look and feel of the timeline items as well as their visual states. The approach is demonstrated in our First Look demo - http://demos.telerik.com/silverlight/#Timeline/FirstLook .

Fix available in LIB Version 2016.2.516.

Available in LIB version: 2015.1.0604

Currently there is no way to pass parameters in the FileUploadFailedEventArgs of the FileUploadFailed event. In the UploadCompleted event such parameters are passed in the HandlerData.CustomData of the FileUploadedEventArgs.

Available in LIB version: 2014.3.1402

It would be nice the DCTDecode filter to handle correctly images that are encoded in CMYK colorspace.

When system DPI is larger than 100% the transition animation is not scaled up with it.
Available in LIB version 2015.2.803 , it will be also available in the 2015 Q3. 

When set the ActiveViewDefinitionIndex to more than 0, the event triggers 3 times, it also depends on what is the ViewDefinition.

Available in LIB version 2016.1.201, it will be also available in the 2016 SP1 Release.

When UserControls are dynamically added in the RibbonView Items collection, they are displayed as RibbonTab Headers. Instead they should create a RibbonTab collection where each control represents the content of a RibbonTab.

UPDATE: An implicit style can not be applied on derived controls as their TargetType is different than the one defined in the implicit style. Basically if you set the style implicitly, the style is applied only on the types that match the TargetType exactly and not on elements derived from the TargetType value. You can find more information on the topic in the remarks section of the Style property definition: http://msdn.microsoft.com/en-us/library/system.windows.style%28VS.95%29.aspx

This is why in order to apply a Telerik predefined style on a UserControl deriving from RadRibbonTab, you  need to add a Style targeting the UserControl type in the Resources of the application. It is best to define that style after merging the Telerik ResourseDictionaries so that you can base the UserControl Style on the predefined "RadRibbonTabStyle".

Importing a document could result in a big UsedCellRange due to the big range of the imported DataValidationRule cell property. The UsedCellRange calculations should ignore this property. This could lead to a performance diminishment when exporting.

When displayed inside a RadWindow, if the window is moved outside the browser, the placeholder gets cut off.
This issue also appears if initally the left side of RadWindow is positioned outside the browser.

The DataContext is not distribute to Large and Small contents in some cases.

Possible workarouns:
1) Declare the DataContext of TileView in xaml, for example:
   <Window.DataContext>
        <local:MainViewModel />
    </Window.DataContext>

2) Assing DataContext Binding to the three contents:
  <telerik:RadFluidContentControl.LargeContent>
                <Grid DataContext="

 <telerik:RadFluidContentControl.Content>
                <TextBox FontSize="16" DataContext="{Binding}"

            <telerik:RadFluidContentControl.SmallContent>
				<TextBlock FontSize="12" DataContext="{Binding}"