The same property is available for MS TooltipService in WPF. 

Implement a mechanism that allows embedding font data when exporting documents.

ApplicationMenu do not have keyboard navigation - pressing arrows do not navigate thru the application menu items.
Declined as a duplicate of: https://feedback.telerik.com/wpf/1352753-ribbonview-applicationmenu-do-not-have-keyboard-navigation.

Add support for axis with multi-level categories
Declined as a duplicate of: https://feedback.telerik.com/wpf/1351027-chartview-add-support-for-axis-with-multi-level-categories

This item is declined because it is wrongly logged and the issue is duplicated with another feedback item. You may follow instead these feedback item which also provides a sample attached project for repairing such invalid files:

https://feedback.telerik.com/Project/143/Feedback/Details/170586-pdfviewer-handle-documents-containing-invalid-cross-reference-table-start-index

This item is declined because there are many PDF annotation types and we are going to create separate items for each type. You may follow some of the existing annotation feedback items listed below or create a new one which the Telerik team is going to approve. Here follows the list of the existing feedback items:
https://feedback.telerik.com/Project/143/Feedback/Details/167439-pdfviewer-support-for-annotations-of-type-stamp
https://feedback.telerik.com/Project/143/Feedback/Details/203379-pdfviewer-support-for-annotations-of-type-popup
https://feedback.telerik.com/Project/143/Feedback/Details/199351-pdfviewer-support-for-freetext-annotation-type
https://feedback.telerik.com/Project/143/Feedback/Details/149974-pdfviewer-highlight-annotation

Silverlight will be end of life in 2021. But if you look at at the currently supported browsers https://en.wikipedia.org/wiki/Microsoft_Silverlight#Desktop_computers you will see it is only running on Internet Explorer 11. All other browsers have canceled support for Silverlight.

Does it really makes sense to still support Silverlight?

I'm asking because of this: https://docs.telerik.com/devtools/wpf/xamlflix-step-by-step-guide/xamlflix-radbarcode. This is the WPF documentation for radBarcode but it effectivly is talking about Silverlight!

It should be possible when user selects multiple cells on the current view with the CTRL key to return the list of these cells with the ScheduleView method.

More info here:
http://www.telerik.com/forums/select-multiple-days-with-ctrl-key

Rendering issues occur when using Hierarchical virtualization mode and bring into view several times. The Headers of some items appear over other Headers.

The feedback item is declined due to duplication with the one below:
http://feedback.telerik.com/Project/143/Feedback/Details/113680-treeview-rendering-issues-when-using-hierarchical-virtualization-mode-and-bring
Please follow it instead.  

Add ability to change visibility of the information layer depends on the zoom range.

DECLINED: Duplicate with http://feedback.telerik.com/Project/143/Feedback/Details/113252-map-support-maplayer-zoomrange-on-informationlayer

The Gauge control should allow to override the whole entire "Content" property of the tooltip like to the ItemToolTipOpening event of ChartArea.

Declined: Duplicate with http://feedback.telerik.com/Project/143/Feedback/Details/113231-gauge-add-ability-to-override-the-content-property-of-the-tooltip

DECLINED: Duplicate with http://feedback.telerik.com/Project/143/Feedback/Details/114177-htmlplaceholder-support-for-webbrowserbrush

Add MouseOver Selection states in the RadRibbonTab control

Decline reason: RibbonView and its elements (including TabControl) are inspired by MS Office products. Since hovering over the selected TabItem in MS Word for example doesn't change its visual appearance it shouldn't in RibbonView as well.
If your project design still requires such appearance then we highly recommend that you edit the Control Template of the TabControl in Telerik.Windows.Controls.RibbonView assembly and add a MultiTrigger Condition (in WPF):
  <MultiTrigger>
                <MultiTrigger.Conditions>
                    <Condition Property="IsMouseOver" Value="True"/>
                    <Condition Property="IsSelected" Value="True"/>
                </MultiTrigger.Conditions>
...
</MultiTrigger>
or add a  <VisualState x:Name="SelectedMouseOver"> to CommonStates VisualStateGroup.

Currently RadRichTextBox supports Html-based and Silverlight printing.

Silverlight printing should be very exact as it simply prints out each page as an Image. Though this type of printing can be really slow for large documents.

Currently page layout in Html printing depends on browser layout and this is why the number of pages in the actual document and browser-printed version can be different. Using absolute positioning in Html hopefully this issue can be resolved and paging/positioning of document elements will be precise.

Add panel element to the TabStripAdditionalContent property. This way it will be easier for the users to add content.

Declined: The existing API for the TabStripAdditionalContent property (of type Object) easily allows the users to customize and insert content depending on their requirements. For instance if you want to use data from ViewModel and list all of its Items you could use the following code:
<telerik:RadRibbonView.TabStripAdditionalContent>
	<ItemsControl ItemsSource="{}" >
		<ItemsControl.ItemsPanel>
			<ItemsPanelTemplate>
				<StackPanel Orientation="Horizontal" />
			</ItemsPanelTemplate>
		</ItemsControl.ItemsPanel>
	</ItemsControl>
</telerik:RadRibbonView.TabStripAdditionalContent>

The MinimizedPopup could be open/closed by using the SelectedIndex property of the RadRibbonView.

A sample implementation could be seen in the attached project.

Add a visual loading indicator to display the progress of the assemblies loading process

Support Documents (RichTextBox) assemblies