7 Answers, 1 is accepted
You may try to subscribe to the SelectionChanged event of the RadComboBox. I am sending you a sample project illustrating one possible approach for handling this scenario.
Maya
the Telerik team

One more question if you could help me. The gridview lost foucs is not firing. I have a gridview data column, and when i press tab, the lost foucs is not firing, Could you see this issue.
Thanks
Zubair
I am not quite able to reproduce the issue you specified as I am not aware of your exact project settings. Thus in order to provide you with any solution, I would need you to elaborate a bit more about your scenario.
Maya
the Telerik team

I have changed a single thing in your previous solution you have sent as a sample.
<Window x:Class="ComboBox_Selection_Changed_Handling_WPF.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
Title="Window1" Height="300" Width="300">
<Grid>
<Grid.Resources>
<Style TargetType="telerik:RadComboBox" >
<EventSetter Event="SelectionChanged" Handler="ComboBox_SelectionChanged" />
</Style>
</Grid.Resources>
<telerik:RadGridView x:Name="RadGridView1" AutoGenerateColumns="False">
<telerik:RadGridView.Columns>
<telerik:GridViewComboBoxColumn DataMemberBinding="{Binding CountryID}" DisplayMemberPath="Name" SelectedValueMemberPath="ID" />
<telerik:GridViewDataColumn DataMemberBinding="{Binding FirstName}"
LostFocus="GridViewDataColumn_LostFocus"
<telerik:GridViewDataColumn DataMemberBinding="{Binding LastName}" />
</telerik:RadGridView.Columns>
</telerik:RadGridView>
</Grid>
</Window>
It is not firing when the focus is lost..
Thanks
The "LostFocus" event comes from the Framework that GridViewColumns inherit in our WPF version of RadGridView. Unfortunately, it is not implemented in the internal logic of the Control.
However, if you share more details about the purpose of using this event, I may be able to provide you with an appropriate solution.
Maya
the Telerik team

My scenario is very simple.
I have a column named quanity of products. What I want is, to do some operation when user enters some quantity based on its value. like
Qty/ unit descriptor / product/ unit price
5 / boxes / pencils / 10
You may handle the CellEditEnded event of the RadGridView and take the NewValue property from the arguments.
Maya
the Telerik team