Clears all the items in the receiver. The text, icon and other
attributes of the items are set to their default values. If the
tree was created with the <code>SWT.VIRTUAL</code> style, these
attributes are requested again as needed.
@param all <code>true</code> if all child items should be cleared
recursively, and <code>false</code> otherwise
@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>
Clears all the items in the receiver. The text, icon and other attributes of the items are set to their default values. If the tree was created with the <code>SWT.VIRTUAL</code> style, these attributes are requested again as needed.
@param all <code>true</code> if all child items should be cleared recursively, and <code>false</code> otherwise
@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 SWT#VIRTUAL @see SWT#SetData
@since 3.2