BCGControlBar Pro for MFC
void CBCGPGridCtrl::AllowRowExtraHeight ( BOOL  bAllow = TRUE)

Enables preview pane.

Use this function to enable preview pane. Preview pane is displayed below a row and the height of rows is increased to accommodate the additional text to be displayed on the row's pane.

bAllowIf TRUE, grid rows will have some additional space to display the preview pane.