Returns the column at the given, zero-relative index in the
receiver. Throws an exception if the index is out of range.
Columns are returned in the order that they were created.
If no <code>TreeColumn</code>s were created by the programmer,
this method will throw <code>ERROR_INVALID_RANGE</code> despite
the fact that a single column of data may be visible in the tree.
This occurs when the programmer uses the tree like a list, adding
items but never creating a column.
@param index the index of the column to return
@return the column at the given index
@exception IllegalArgumentException <ul>
<li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</li>
</ul>
@exception SWTException <ul>
<li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
<li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
</ul>
Returns the column at the given, zero-relative index in the receiver. Throws an exception if the index is out of range. Columns are returned in the order that they were created. If no <code>TreeColumn</code>s were created by the programmer, this method will throw <code>ERROR_INVALID_RANGE</code> despite the fact that a single column of data may be visible in the tree. This occurs when the programmer uses the tree like a list, adding items but never creating a column.
@param index the index of the column to return @return the column at the given index
@exception IllegalArgumentException <ul> <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</li> </ul> @exception SWTException <ul> <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> </ul>
@see Tree#getColumnOrder() @see Tree#setColumnOrder(int[]) @see TreeColumn#getMoveable() @see TreeColumn#setMoveable(bool) @see SWT#Move
@since 3.1