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

My FindFullMatchIndex method returns -1 when an item is not found. Instead of selecting no items and leaving the scroll position where it's at like the default search text behavior; the combobox scrolls the list to the top and selects the first item in the list.

This happens only with editable ComboBox in Silverlight.

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.

When the ItemsSource for a RadComboBox is bound to a collection with two different properties, id and ID.  When I bind SelectedValuePath to one of the properties, changing selection throw error:  "Ambiguous match found" exception.

When moving through elements(checkbox+ text) in RadCombobox with the keyboard, focus of combobox is not changed as expected.
Sample project attached.

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

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.

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.