Returns the number of items contained in the receiver
that are direct item children of the receiver. The
number that is returned is the number of roots in the
tree.
@return the number of items
@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 number of items contained in the receiver that are direct item children of the receiver. The number that is returned is the number of roots in the tree.
@return the number of items
@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>