When Tab key is pressed inside of the drop down portion of the ComboBox the next control to be focused.

Available in the 2016 Q1 Release: Added IsDropDownTabNavigationEnabled property which provides an option to disable the Tab navigation in the dropdown of non editable ComboBox.

Add Events for when the ClearSelectionButton is clicked.

onSelectionClearingEvent (cancelable preview event)
OnSelectionClearedEvent

This way we can easily handle the clearing of non-nullable datatypes

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

A two-way relation between CurrentItem and SelectedItem when the ItemsSource is ICollectionView.

Dangalov: This feature will be recieved automatically when replacing ListBox with RadListBox.