Sets the receiver's alpha value which must be
between 0 (transparent) and 255 (opaque).
<p>
This operation requires the operating system's advanced
widgets subsystem which may not be available on some
platforms.
</p>
@param alpha the alpha value
@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>
Sets the receiver's alpha value which must be between 0 (transparent) and 255 (opaque). <p> This operation requires the operating system's advanced widgets subsystem which may not be available on some platforms. </p> @param alpha the alpha value
@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>
@since 3.4