We are confused by this XAML snippet. What is this MyCustomFilter thing? How are you using it?
By the way, this XAML that you have pasted is completely illegal. You have placed grid columns outside the grid and you have placed this thing MyCustomFilter inside a column. Both of these are impossible.
It would be best if you open a separate support ticket, attach a runnable sample project and tell us (in great detail) what exactly ware you trying to achieve.
the Telerik team
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