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Again, Getting control inside datatemplate from code behind

Posted By:      Posted Date: August 27, 2010    Points: 0   Category :WPF
HI, All: This problem comes back to bite me again. I had a similar problem before but I changed the customer control to user control and define the click event in the xaml. But this time I have to stick with the customer control. I searched the internet and there are a lot of examples but in my situation, I still got null object. I have a CUSTOMER control which derives from treeview. The hierachicalDataTemplate for the treeview is following:     <HierarchicalDataTemplate         x:Key="CheckBoxItemTemplate"         ItemsSource="{Binding SubFolder}"         >         <StackPanel Orientation="Horizontal">             <CheckBox             x:Name="PART_CheckBox"             Focusable="False"             IsChecked="{Binding IsSelected}"             VerticalAlignment="Center"                 &nbs

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