1. A system for controlling an operation of a shader comprising: a declarative programming model that enables declarative statements of a declarative language to be used that control an instantiation and operation of a shader in a declarative presentation framework, wherein the shader is operable to run on a graphics processing unit and the declarative programming model enables a software application to use the declarative programming model to utilize the graphics processing unit for graphical effects in the software application, wherein the declarative programming model is operable to allow brushes to be used as inputs to the shader.