BCGControlBar Pro for MFC
void CBCGPGridCtrl::EnableGroupByBox ( BOOL  bEnable = TRUE)

Enables or disables visual grouping of columns.

Call this function to enable or disable visual grouping of columns. When this option is enabled, the grid control shows a box where you can drag and drop columns (header items). The order of columns in this box defines the groups.

bEnableSpecifies whether to enable or disable visual grouping.