Return the index of the specified tab or -1 if the tab is not
in the receiver.
@param item the tab item for which the index is required
@return the index of the specified tab item or -1
@exception IllegalArgumentException <ul>
<li>ERROR_NULL_ARGUMENT - if the listener is null</li>
</ul>
@exception SWTException <ul>
<li>ERROR_THREAD_INVALID_ACCESS when called from the wrong thread</li>
<li>ERROR_WIDGET_DISPOSED when the widget has been disposed</li>
</ul>
Return the index of the specified tab or -1 if the tab is not in the receiver.
@param item the tab item for which the index is required
@return the index of the specified tab item or -1
@exception IllegalArgumentException <ul> <li>ERROR_NULL_ARGUMENT - if the listener is null</li> </ul>
@exception SWTException <ul> <li>ERROR_THREAD_INVALID_ACCESS when called from the wrong thread</li> <li>ERROR_WIDGET_DISPOSED when the widget has been disposed</li> </ul>