Is there a way to replace the Eclipse JDT's code completion list with a multi-level tree?

Question

I know that the eclipse code completion widget can be customized to add new suggestions and even to change the order.

I'm wondering whether there's a way to replace the current list format (or single-level tree, if this is a tree control) with a tree of multiple levels.

Thus, for example, instead of selecting from a list of methods sorted by name, I will select from a category and then from a subcategory, and then from the items.

I'm not too familiar with that part of the SDK, but I'd like to know if this is feasible.

Thanks!