Our suggestion in this scenario is to set the TouchManager.TouchMode property to None, since the RadGridView handles touch events and setting this property will allow both touch and click events to propagate to the Click event.
Here is an example:
<telerik:RadComboBox telerik:TouchManager.TouchMode="None" >
<telerik:RadComboBoxItem Content="Item 1" />
<telerik:RadComboBoxItem Content="Item 2" />
<telerik:RadComboBoxItem Content="Item 3" />
<telerik:RadComboBoxItem Content="Item 4" />
</telerik:RadComboBox>
Regards,
Vladimir Stoyanov
Progress Telerik