How can I get the ClientRect() for the CAknView derived class to occupy the whole display?

I want an app to use full screen mode. Using the code in wiki (repeated in some other threads) works OK until a system dialog appears (eg. low battery). When that happens the area occupied by the CB is left on screen.

To try to check what was going on, in a method inside my CAknView derived class I did the following check:

TRect rect = static_cast<CMyAppUi*>(CEikonEnv::Static()->AppUi())->ApplicationRect();
TRect rect2 = static_cast<CMyAppUi*>(CEikonEnv::Static()->AppUi())->ClientRect();

TRect currentrect = ClientRect();

The two blue lines return a TRect that occupies the full screen.
The red line returns a TRect that occupies all the screen except the control bar area.
I wonder how can I get the ClientRect() for the CAknView derived class to also occupy the whole display (?)