1. A computer-implemented method for performing automated user-interface layout testing, the method comprising: executing a pre-defined set of operations for a program; storing a first representation of a user interface for the program subsequent to executing the operations; automatically tagging the first representation with a unique tag, wherein the tag identifies an environment, workflow, and time frame in which the first representation is obtained, which allows identification of multiple images of the same workflow for comparison; automatically selecting, based on the unique tag, one or more previously stored valid representations tagged with the same workflow for comparison with the first representation; and comparing the first representation against each of the one or more validated representations to determine a difference between the representations, thereby facilitating detecting changes that affect the user interface, wherein said comparing involves: receiving a specification that describes an acceptable level of change between the first representation and a validated representation; and determining whether the difference between the first representation and any of the one or more validated representations exceeds the acceptable level of change.