1. A computer-implemented method comprising: receiving a first selection of a first application for parallel presentation in an immersive environment on one or more displays associated with a computing device; responsive to the first selection, determining an amount of space of a primary region of the immersive environment to allocate for display of the first application, the primary region of the immersive environment not having system chrome; responsive to the first selection, causing content of the first application to be displayed in the space of the primary region allocated for display of the first application; receiving a second selection of a second application for parallel presentation with the first application in the immersive environment on the one or more displays associated with the computing device; responsive to the second selection, determining an amount of space of a non-primary region of the immersive environment to allocate for display of the second application, the non-primary region of the immersive environment not having system chrome, the amount of space of the non-primary region to allocate for the display determined based on a predefined fill, no fill, or fill to maximum size requirement of requirements specified in the second application, the amount of space being: for the predefined fill size requirement, all available space in the non-primary region; for the predefined no fill size requirement, an amount of space within the non-primary region equal to the minimum size specified by the predefined no fill requirement; or for the predefined fill to maximum size requirement, all available space within the non-primary region equal to or less than a maximum size specified by the predefined fill to maximum size requirement; responsive to the second selection, causing selected content of the second application to be displayed in the space of the non-primary region allocated for display of the second application, the selected content of the second application based on the requirements specified in the second application and the selected content being less than content of the second application that would be displayed in the space of the primary region allocated for display; and enabling interaction with the second application through the non-primary region of the immersive environment and with the first application presented in the primary region of the immersive environment.