8. A computer program product comprising a non-transitory computer usable storage medium storing computer usable program code for extensible context based user interface simplification for a model driven development tool, the computer program product comprising: computer usable program code for executing the model driven development tool in a memory of a host computer, the tool comprising a multiplicity of user interface components including tool items and also model components of a model loaded for processing in the tool; computer usable program code for registering different ones of the tool items in a tool item registry in association with corresponding contexts of the model driven development tool; computer usable program code for detecting a context of the contexts change to a new context in the model driven development tool based upon a selection of a new one of the model components in the model driven development tool, wherein detecting the context change to the new context in the model driven development tool comprises detecting the selection of the new model component associated with a context object in the model driven development tool, the context object providing the new context; computer usable program code for locating ones of the tool items in the registry mapped to the new context; and, computer usable program code for displaying the located tool items in the model driven development tool.
10. The computer program product of claim 8 , wherein the computer usable program code for locating tool items mapped to the new context, comprises: computer usable program code for locating a plurality of tool item providers providing tool items for the new context; and, computer usable program code for selecting only ones of the tool items mapped to the new context.