In one general aspect, a computer-readable storage medium storing instructions that when executed cause one or more processors to perform a process that can include sending from a client device to a host device an indicator of a size of a target display area of a moving window session with respect to a host display area of an application operating at the host device where the application can be remotely controlled via the client device. The process can include analyzing a stream of images associated with the target display area of the moving window session and defining at the client device a plurality of regions within the target display area based on the analyzing. The process can also include modifying the moving window session without terminating the moving window session and without establishing a new moving window session.