It would be quite useful for me to have a pane in both Materials and Appearances for Materials that are in use within a project through out the various components in different designs within the same project and that changes in this pane would affect the other designs.
I quite often use a modular approach, similar to Solidworks where I have different parts in different files and one assembly file. But I generally want to keep the same colours and materials and when I change one of them I have to go through each component to put in the same values.
Or, when I'm creating a new component for the project I have to use 'My appearances' to transfer the appearance from one design to another.