在vuforia unity 3d中暂停/冻结具有可跟踪活动的场景

I am developing an app with vuforia Cloud Recos. I want to add the feature of allowing the user to pause the page so she does not have to keep pointing the device on the target to view the trackable. This is pretty useful when I want to show texts. Is there anyway to achieve that on Unity3D ? A good example is Microsoft's Here City Lens app which includes a button to pause the page as the screenshot shows; I am developing an app with vuforia Cloud Recos