You could repair the invalid file using the project from the attachment.

If the appearance is defined using a non-existing object reference in PDF document, NullReferenceException is thrown on import. 

In Expression Dark theme when you have a TextBlock inside a FluidContentControl the foreground is not updated.

When using a diagram in the theme Windows8, the all the text in the RadComboBox controls inside SettingsPaneTextControl is not showing.

Please see the attached file for example.

In a newly created empty Silverlight project, the Theme is set to Windows 8:

StyleManager.ApplicationTheme = new Windows8Theme();

Create a RadDiagram in a xaml file

<telerik:RadDiagram x:Name="diagram">
            <telerik:RadDiagramTextShape Content="Test" />
            <primitives:ItemInformationAdorner.AdditionalContent>
                <telerik:SettingsPane Diagram="{Binding ElementName=diagram}" />
            </primitives:ItemInformationAdorner.AdditionalContent>
        </telerik:RadDiagram>

And the text in the RadComboBox controls inside SettingsPaneTextControl is not visible.

most other themes work fine, but Window8 is not.

I already updated to the latest Telerik Silverlight libraries.

 

This reproduces only if the FlipDuration property of RadBook is set to 0. 

To work this around set the FlipDuration to a bigger value. For example: FlipDuration="0:0:0.001"

The items of the RadComboBox control in the SettingsPane Text tab are not visible when the Windows8 theme is applied using StyleManager.

Users want to be able to resize columns of RadPivotGrid at runtime, similar to RadGridView.

This feature is available with our latest official version - R1 2019.

The regular ComboBox goes through all of the starting with the same letter items when pressing the same key multiple times. RadComboBox currently always highlights the first one.
In addition, the case where starting to type couple letters, will select the matched item with StartsWith

Allow users to expand properties of a complex type in order to reveal the list of that type's properties.

The feature will be available in R1 2019, scheduled for the mid of January 2019. 

The colors are different everytime the file is opened in the viewer.

Available in R1 2017 Release

The DropDownMenu is incorrectly positioned when the default TabStripPlacement is changed - if the TabStripPlacement is set to Bottom/Left/Right, the DropDownMenuis displayed at the top left corner of the screen.

The current workaround is to edit the control template of the control and set the MinWidth of the PART_ListBox element:

                   <Popup x:Name="PART_Popup">
						<Grid x:Name="PopupRoot">
							<telerik:RadListBox x:Name="PART_ListBox"
												 MinWidth="{TemplateBinding MinDropDownWidth}"
												MaxHeight="{TemplateBinding MaxDropDownHeight}"
                            ItemsSource="{TemplateBinding FilteredItems}"
                            ItemTemplate="{TemplateBinding DropDownItemTemplate}"
                            FontFamily="{TemplateBinding FontFamily}"
                            FontSize="{TemplateBinding FontSize}"/>
							<Border
                            Background="{Binding Background, ElementName=PART_ListBox}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="1"
                            Width="{Binding ElementName=PART_ListBox, Path=Width}"
                            Visibility="{Binding ElementName=PART_NoResultsContentPresenter, Path=Visibility}">
								<ContentPresenter x:Name="PART_NoResultsContentPresenter"
                                MinWidth="{TemplateBinding MinDropDownWidth}"
                                MaxHeight="{TemplateBinding MaxDropDownHeight}"
                                Content="{TemplateBinding NoResultsContent}"
                                ContentTemplate="{TemplateBinding NoResultsContentTemplate}"
                                Visibility="Collapsed"
                                Margin="5 4"/>
							</Border>
						</Grid>
                   </Popup>