return;
try {
X11.Window win = getDrawable(w);
if (alpha == 1f) {
x11.XDeleteProperty(dpy, win,
x11.XInternAtom(dpy, OPACITY,
false));
}
else {
int opacity = (int)((long)(alpha * OPAQUE) & 0xFFFFFFFF);
IntByReference patom = new IntByReference(opacity);