1. A graphical object classification system, comprising: a processor; and a non-transitory processor-readable medium comprising: an acquisition module to access a two dimensional bitmap representation of a graphical object generated from a parsed screenshot of a graphical user interface (GUI); a signature generation module to generate an appearance-invariant signature of the graphical object based on the bitmap representation of the graphical object, wherein the appearance-invariant signature comprises a composite of two or more signature vectors that vary little in response to changes in shape, size, orientation, and visual layer appearance of the graphical object, and each of the signature vectors includes attributes based on operations on the bitmap representation of the graphical object comprising integration along a first dimension, differentiation of the integration along a different second dimension, and domain transformation of the differentiation into at least one of Fourier magnitude components and log-domain transforms; and a classification module to classify the graphical object based on the appearance-invariant signatures, wherein the graphical object is classified into a class and the graphical object after a change in appearance is classified into the same class when the respective appearance-invariant signatures before and after the change share substantially common attributes.