Returns a Boolean value that indicates whether the column at a given index is selected.
Original signature is '- (BOOL)isColumnSelected:(NSInteger)columnIndex'
Available in Mac OS X v10.0 and later.


- columnIndex (NSInteger)
- The index of the column to test.

YES if the column at columnIndex is selected, otherwise NO.

- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)