Use this column to create a complex custom dropdown window. For instance, it can be used to display master-detail relationships. Assume, ExpressQuantumGird displays master data, whereas another grid (it can be a standard TDBGid) displays detail records. Specify this standard grid as a popup control for TdxDBGridPopupColumn and users will be able to view detail records from a button press event within the TdxDBGridPopupColumn dropdown window.