Retrieves the current header options.
The returned value can be a combination of the following flags:
- BCGP_GRID_HEADER_MOVE_ITEMS: allow to drag and drop header items.
- BCGP_GRID_HEADER_HIDE_ITEMS: allow to hide column when drag and drop.
- BCGP_GRID_HEADER_SORT: allow mouse click on header item to change sort order of the column.
You can call EnableHeader() to set the new combination of flags.