The default list of values in the drop-down list of a filter enabled column for a FlyGrid whose DataSource is a DataTable and for which the user has previously selected a filter includes only the values that match the previously selected filter. This behavior is inconsistent with the behavior of the FlyGrid Filters and Summaries example and with Microsoft Excel.
The Filters and Summaries example always includes all values for all columns (except Order Date, which uses a custom filter). The difference in behavior may be due to the fact that the example uses a DataSet for the DataSource.
The algorithm used by Microsoft Excel is more complicated. If only one column has a filter, it always shows all values. If more than one column has a filter, the list of values for the second filter is limited by the first filter.
I had to create a custom filter to work around this FlyGrid defect.