SMART datagrid v.1 > Classes > ColumnHeader
Specify as the distance between check box or image being displayed in header cell and text. If this value is undefined, it will use GridHeader.itemGap.
column.setHeader({
itemGap: 4,
itemOffset: 2
});
// or, set individually.
column.header().setItemGap(4);
// can also use setProperty.
column.setProperty('header.itemGap', 4);