Changing callback based on the grammar of the active text editor?

Is it possible to change the callback for a button based on the grammar of the active text editor?

The issue names no files, tests, or entry points and only asks whether grammar-dependent callbacks are possible. First clarify the expected button and callback behavior, then locate the toolbar's callback handling and determine how the active editor grammar should select it; done means the requested grammar-based behavior is implemented and verified.

Written by the indexing model from the issue text.