What class is this?

>This is my first time making use of the _SuperMover class and I have a couple questions I'm sure others have already solved.
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>My form consists of a drop down list of valid departements for a user. When the user selects a department, I fill the available choices lists for the mover class with data based on a query.
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>  SELECT StatusDesc FROM CurList1 INTO ARRAY laChoices
>  thisform.pageframe1.page1._suPERMOVER1.initchoices(@laChoices)
>

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>The first question is, not all departments will have records returned from the query, and this causes an error because the array is invalid, so how to I clear the lists (both of them).
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>The second question is, I have a next button on the form that is disabled until they have at least one option selected in the selected part of the mover list. I put the following code in the form's refresh method, but it didn't seem to have any effect.
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>thisform.pageframe1.page1.command1.Enabled=IIF(thisform.pageframe1.page1._suPERMOVER1.lstRight.ListCount>0,.t.,.f.)
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>Thanks for any pointers
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>Kirk