Showing the app bar conditionally in windows store apps

Hi,

Usually in windows store apps, if I have a screen with app bar the default behavior is that the app bar becomes visible when I right click on the screen.

I want to control this. I want to decide based on some conditions when it shall be visible on right click and when not.

I have a screen with app bar and a pop up. I want the app bar not to become visible when pop is open and I do right click. But it should be come visible when the pop up is closed and when I right click.

Can some body tell me how to perform this. Seems like I need set some property of app bar.