In our paper about flexible elision, we presented an approach to specify information about brackets, symbols, and other parts of mathematical formulae that can be elided for enhanced clarity as a part of a notation specification for symbols in a content markup format like OpenMath. We discussed how information about elided parts and their "degree of elidability" can be transferred to an interactive output format like Presentation MathML or HTML. Actually, in Presentation MathML, this interactivity is not yet possible due to a missing specification and implementation of a CSS and DOM API for MathML in a browser. Therefore, we implemented a demo in plain HTML, which we encourage you to try out. You need a browser that understands DOM Level 3 XPath Queries; Firefox 2 and Opera 9 do, for example. This is how you get the best experience:

1. In the inner frame, open the document with the demo formula. (The other document is just an ordinary document generated from an OMDoc source, but it is not a fine-tuned showcase for the demo.)
2. Step by step increase the threshold for showing elidable brackets and watch the upper formula expand. Also note the different colors of highly elidable brackets. (The latter feature only works in Firefox.)
3. Then increase the threshold for showing elidable type annotations and watch the lower formula expand.
4. Finally, reduce the threshold for showing brackets again and watch the brackets of the right-associative function type operator in the lower formula disappear in the last step.
5. Note that, while both examples have been fine-tuned manually for the demo, they could have been generated from OMDoc - this holds for the bracket example, at least. The information about the inferability of type annotations that is required for the elision in the type annotation example would have had to be added in a post-processing step after transforming OMDoc to HTML.