Constructs a new instance of this class given the display
to create it on and a style value describing its behavior
and appearance.
<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><p>
Note: Currently, null can be passed in for the display argument.
This has the effect of creating the tracker on the currently active
display if there is one. If there is no current display, the
tracker is created on a "default" display. <b>Passing in null as
the display argument is not considered to be good coding style,
and may not be supported in a future release of SWT.</b>
</p>
@param display the display to create the tracker on
@param style the style of control to construct
@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 the display to create it on and a style value describing its behavior and appearance. <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><p> Note: Currently, null can be passed in for the display argument. This has the effect of creating the tracker on the currently active display if there is one. If there is no current display, the tracker is created on a "default" display. <b>Passing in null as the display argument is not considered to be good coding style, and may not be supported in a future release of SWT.</b> </p>
@param display the display to create the tracker on @param style the style of control to construct
@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#LEFT @see SWT#RIGHT @see SWT#UP @see SWT#DOWN