Lwuit S40 Dimmed Forms

I am developing a LWUIT S40 app. The guidelines specify that when a dialog is on, the background, including status bar, header bar, category bar, must be dimmed – 60% black.

I think that this will happen automatically, but it doesn't.

Anybody knows a way to do that? To dim the header bar and the category bar, like this capture (which is an lcdui alert)

.

I prefer to use native Alert from nokia LCDUI. the LWUIT for Series 40 allow us to combine the LCDUI component along with LWUIT component.

For example, here's my code:

Alert loading = new Alert("MIG33", "Loading user", null, null);
loading.setIndicator(new Gauge(null, false, Gauge.INDEFINITE, Gauge.CONTINUOUS_RUNNING));
javax.microedition.lcdui.Display.getDisplay(this).setCurrent(loading);

Since LWUIT has its own Display class we use in the midlet. It has to be written like above. So it can be differenced with the Display from LCDUI.