Improve the design-time support of the TabControl. For example add an option to add new RadTabItems in the control.

Exceptions are occuring on ALL bindings, not just with RelativeSource

Command="{Binding AddCommand}"

will also raise an exception.

Add a visual state for the selected tab item representation in the DropDown menu of the TabControl.

RadTabControl is currently designed to support scrolling of RadTabItems only when any of them is currently focused. An ability to scroll RadTabItems without explicitly focusing them should be provided.

If you define two UserControls in a project and you add two RadTabControls - one RadTabControl per UserControl, then in design-time you can only change the selection of one of the tab components.

Using  ArcGIS API for Silverlight/WPF version 2.1 in the TabControl throws exception in design-time

When the SelectedIndex property is read during animation the CLR wrapper will throw InvalidCastException because of invalid cast to int. The object returned from GetValue is DeferredReference object.

Change the TabItems layout when the TabControl OverflowMode="Wrap" with TabStripPlacement="Bottom" :
1. Let's say the wrap results in 3 lines. What we would expect is line 1 and 2 to be filling the entire width and line 3 to be partially filled. What we experience is line 1 partially filled and lines 2 and 3 filling the entire width 
2. When clicking on an item the lines swap around. The partially filled line can end up on top, in the middle or on the bottom. Clicking on items that cause tab rows to move up should re-flow the wrap.
3. Ideally - to look good - the logic should stretch the 'complete' rows to the entire width - i.e. it should adjust tab sizes to fill the entire width available on 'full' rows.

Can't apply transitions when changing the visual state of the RadTabControl or its items

The CommonStates of the control aren't applied and this is why you can't add any storyboards for the normal and disabled state of the control.

The selected item could have a different header template so that it will be differentiated from the rest of the  tabs.

The TabControl ScrollMode property doesn't work as expected when set to "Item"

Display in overflow menu only the items that are not visible in the tab strip.

When you have implicit DataTemplates applied to items the binding expression is lost on selection changed.

When the window of an application that has a TabControl with Left/Right TabStripPlacement is resized, the measure of the TabStrip is incorrect and the ScrollButtons are in Disabled state. All Tabs should be visible when the window is in its normal state and should be scrollable.

Introduce "Add new tab" button as in the RadTabbedWindow control which creates a new tab upon click.

TabControl: The tab items and their content are not disposed correctly due to the RadTabItemAutoamtionPeer.

Basically I want to see only full tabs, not part of a tab.  Those tabs that aren't visible should be displayed in the dropdown only, the tabs that are visible should not be displayed in the dropdown, and the tab control should resize (to a shorter width) to only show tabs that are visible

When you have the TabStripPlacement property set to something other than Top and you try to hide the TabControl border by setting the BorderThickness property to 0. The border is still shown. If you have TabStripPlacement set to Top the border disappears.

As a workaround set the BorderBrush property of the RadTabControl to "Transparent".

Selecting tabs with same names from the drop down menu always selects the first one.