Currently filtering with virtualized RadComboBox is not supported as the filtering feature works with the containers (changes their Visibility).

The initial selection doesn't work when RadComboBox is placed in a DataTemplate (examples: ContentControl.ContentTemplate, GridViewDataColumn.CellTemplate) and the SelectedValuePath property of the control is set in a Style DataTrigger. To reproduce this the Binding of the DataTrigger should use a converter.

To work this around avoid using a binding in a DataTrigger to set the SelectedValuePath. Set the property directly on the RadComboBox instance, or use another technique based on your requirements.

In a touch scenario, when there are RadComboBox instances one below the other, selecting an item from a RadComboBox opens the RadComboBox instance, which is below the selected item. 

This is present when there is a global Style that targets the native WPF ScrollViewer element, which sets its PanningMode property to Both. 

To work this around, set the TouchManager.TouchMode to HitTestHidden, in order to exclude the RadComboBox from the TouchManager's events propagation.

Currently RadComboBox supports filtering of the data when IsEditable is True. 

Add a mode where a search box is displayed (when IsEditable is False) in the drop down of the control.  The searchbox should filter the items in the dropdown.

Currently, the RadComboBox provides support for single or multiple selections. We can add an Extended selection mode similar to the one present in the RadListBox control.

Add NoResultsContent and NoResultsContentTemplate properties to the RadComboBox control. 

Currently, the drop down of RadComboBox contains only the RadComboBoxItems and the Clear Selection button. Add new content presenter that allows you to include extra visuals, like buttons or text.

The feature is similar to the AdditionalContent of RadTabControl. 

The RadComboBox control could provide SelectAll button or template functionality. This way the user can choose whether to use the default button or create a custom select all behavior.

In this case, the control is bound to a collection of strings. The collection contains equal string values. ("h1","h2","h1"). When the first item is selected and afterward we select the last one, will not trigger the SelectionChanged event. This behavior could be improved.

 

Currently, the first filtered item of the control is selected once a search (with IsTextSearchEnabled=True) is performed. Users should be able to control whether this happens or if the selection needs to be skipped.

Currently, the EmptyText is shown in a TextBlock which cannot be customized. Add a EmptyTextContent or EmptyTextVisualStyle properties to allow customizing the UI of the empty text. 

The RadListBox has an attached property for mvvm binding of SelectedItems - https://docs.telerik.com/devtools/wpf/controls/radlistbox/features/selecteditemssource.

 

Please support SelectedItemsSource for RadComboxBox too.

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;
    }

Currently the control scrolls by group.