Constructs a new instance of this class given its parent
(which must be a <code>Tree</code> or a <code>TreeItem</code>),
a style value describing its behavior and appearance, and the index
at which to place it in the items maintained by its parent.
<p>
The style value is either one of the style constants defined in
class <code>SWT</code> which is applicable to instances of this
class, or must be built by <em>bitwise OR</em>'ing together
(that is, using the <code>int</code> "|" operator) two or more
of those <code>SWT</code> style constants. The class description
lists the style constants that are applicable to the class.
Style bits are also inherited from superclasses.
</p>
@param parentItem a tree control which will be the parent of the new instance (cannot be null)
@param style the style of control to construct
@param index the zero-relative index to store the receiver in its parent
@exception IllegalArgumentException <ul>
<li>ERROR_NULL_ARGUMENT - if the parent is null</li>
<li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the parent (inclusive)</li>
</ul>
@exception SWTException <ul>
<li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
<li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
</ul>
Constructs a new instance of this class given its parent (which must be a <code>Tree</code> or a <code>TreeItem</code>), a style value describing its behavior and appearance, and the index at which to place it in the items maintained by its parent. <p> The style value is either one of the style constants defined in class <code>SWT</code> which is applicable to instances of this class, or must be built by <em>bitwise OR</em>'ing together (that is, using the <code>int</code> "|" operator) two or more of those <code>SWT</code> style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses. </p>
@param parentItem a tree control which will be the parent of the new instance (cannot be null) @param style the style of control to construct @param index the zero-relative index to store the receiver in its parent
@exception IllegalArgumentException <ul> <li>ERROR_NULL_ARGUMENT - if the parent is null</li> <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the parent (inclusive)</li> </ul> @exception SWTException <ul> <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li> <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li> </ul>
@see SWT @see Widget#checkSubclass @see Widget#getStyle