Returns the application defined property of the receiver
with the specified name, or null if it has not been set.
<p>
Applications may have associated arbitrary objects with the
receiver in this fashion. If the objects stored in the
properties need to be notified when the display is disposed
of, it is the application's responsibility to provide a
<code>disposeExec()</code> handler which does so.
</p>
@param key the name of the property
@return the value of the property or null if it has not been set
@exception SWTException <ul>
<li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
<li>ERROR_DEVICE_DISPOSED - if the receiver has been disposed</li>
</ul>
Returns the application defined property of the receiver with the specified name, or null if it has not been set. <p> Applications may have associated arbitrary objects with the receiver in this fashion. If the objects stored in the properties need to be notified when the display is disposed of, it is the application's responsibility to provide a <code>disposeExec()</code> handler which does so. </p>
@param key the name of the property @return the value of the property or null if it has not been set
@exception SWTException <ul> <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> <li>ERROR_DEVICE_DISPOSED - if the receiver has been disposed</li> </ul>
@see #setData(String, Object) @see #disposeExec(Runnable)