1. A physical computer-readable medium storing computer-executable instructions that are executed on a processing device, the medium storing: one or more instructions for displaying at least a portion of a block diagram of an executable model of a dynamic system on a display device, the block diagram of the executable model comprising one or more blocks arranged in one or more levels according to an internal hierarchy of the block diagram of the executable model; one or more instructions for displaying a graphical representation of the internal hierarchy of the block diagram of the executable model on the display device, the graphical representation representing the internal hierarchy of the block diagram of the executable model with one or more icons; one or more instructions for selecting one of the one or more icons that reference the level; one or more instructions for accessing the selected one of the one or more levels of the block diagram of the executable model through the graphical representation; one or more instructions for receiving a first input; one or more instructions for selecting a first block of the block diagram of the executable model on the graphical representation based on the received first input; and one or more instructions for receiving a second input.