I've been thinking about how much a feature like this would help - being able to mouseover (or click) a label/link/fragment of text and have a preview of the appropriate content of that label/link/fragment pop up, either in an overlay or secondary window.

The straightforward use for this would be to click 'Figure 2.7' when reading a book and having said Figure pop up without changing my main reader view, of course, but other uses come to mind. Click/mouseover a reference, see the apropriate entry in the Bibliography, etc.

I realize there may be a huge amount of complexity with a general solution - e.g. for documents in which no metadata is available linking an instance of 'Figure 2.7' with the actual figure would be challenging. But even an straighforward showing of the 'next instance' of the text might suffice for various cases, and immensely help with the reading flow of books and papers

I'm wondering if any such feature exists in a generally available PDF reader. Creative workarounds (e.g. copious usage of bookmarks and 'navigate to previous view') also welcome in the comments.