Show sub models using different symbol in ModelBuilder

[LindsayRaabe_FPCWA]

When in Model Builder, it would be really useful if Sub Models were highlighted as being submodels and not just another step/tool in the chain. When my colleagues are editing/troubleshooting models that I have created, it's not always inherently obvious to them that there are submodels present unless I do something like the below. A simple highlighted border around the yellow tool symbol, or asterix against the name with a label. Some idea examples below. 

Current default display:

Submodel with border:

Submodel with Asterix and associated label: