The combobox lists in Windows 10 settings (see attached pictures) have an interesting behavior which could be integrated by Telerik combox controls. The behavior is as following: when the listbox is opened, it appears above the combobox control with the selected item highlighted. And the placement of the listbox can change if the first item is selected (displayed down direction) or the last item is selected (display up direction).

It's difficult to explain that with simple words, so I suggest to see attached pictures to understand my request.

The OnLostFocus is triggered when the control gets the focus and is not triggered after the focus is lost. The current call stack is as follows:
- The control gets the focus 
- OnGotFocus is hit
- OnLostFocus is hit incorrectly
- The focus is removed from the control
- The OnLostFocus is not hit and it should be

As a workaround you can hook to these events in the constructor of the custom ComboBox:

    public MyRadComboBox()
    {
        this.GotFocus += MyRadComboBox_GotFocus;
        this.LostFocus += MyRadComboBox_LostFocus;
    }

Available in the 2016 R3 Release.

Please check our help article for more information: 
http://docs.telerik.com/devtools/wpf/controls/radcombobox/features/multiple-selection

When "TextSearchMode" is set to "Contains", IsEditable="True" and IsReadOnly="True": it should be possible to select all or some of the text and by pressing delete or backspace the selected text should be removed.

After making a selection in the control and changing the theme two times in a row an InvalidOperationException is thrown about the animation.

Currently the control scrolls by group.

Place a RadComboBox in the GridViewColumn header and set SelectedIndex in the xaml. The SelectionChanged event is fired, but the command is not executed.

As a workaround you can set the SelectedIndex in xaml instead of on the Loaded event,

When the ComboBox is non editable.