Returns <code>true</code> if this GC is drawing in the mode
where the resulting color in the destination is the
<em>exclusive or</em> of the color values in the source
and the destination, and <code>false</code> if it is
drawing in the mode where the destination color is being
replaced with the source color value.
@return <code>true</code> true if the receiver is in XOR mode, and false otherwise
@exception SWTException <ul>
<li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
</ul>
Returns <code>true</code> if this GC is drawing in the mode where the resulting color in the destination is the <em>exclusive or</em> of the color values in the source and the destination, and <code>false</code> if it is drawing in the mode where the destination color is being replaced with the source color value.
@return <code>true</code> true if the receiver is in XOR mode, and false otherwise
@exception SWTException <ul> <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> </ul>