reftex-mouse-view-crossref
reftex-mouse-view-crossref is an interactive autoloaded Lisp function in `reftex-dcr.el
'.
(reftex-mouse-view-crossref EV)
View cross reference of \ref or \cite macro where you click.
If the macro at point is a \ref, show the corresponding label definition.
If it is a \cite, show the BibTeX database entry.
If there is no such macro at point, search forward to find one.
With argument, actually select the window showing the cross reference.