Systems, including handheld computing devices that include system code stored within the memory and adapted to be executed by the processor. The system code can process an input byte stream that is representative of contents to be displayed on the touch sensitive display and can generate a content document file representative of an internal representation of the content. A tool document file may also be stored in the memory and may provide an internal representation of a document providing an image that is representative of a graphical tool. Associated with a tool document can be tool code that is capable of processing the content document file to create an internal representation of the contents that presents the content in a manner that achieves a display effect associated with the tool. The device will also include parsing code that processes the content document file, the tool document file, and the processed internal representation to generate a screen document for display on the touch sensitive display in a manner that portrays the display effect.