Designer issues for DataGrid within custom control

[Matt Sokol]

I am building a custom control that will contain a DataGrid among
other server controls. I expose the child controls as public
properties so their complete set of individual properties can be
configured through the designer. This works well with almost all
controls I have used in this manner, except the DataGrid. The problem
is when the set of properties for the DataGrid is displayed in the
designer, clicking the Columns property generates an error. Normally
this would invoke the Property Builder dialog, but instead the
following error occurs: "Object reference not set to an instance of an
object."

Any help would be appreciated.
Thanks,
Matt Sokol