Re: Sun optical mice, circa 1985
To be fair, in the early '90s most Sun gear at Unis world-wide was still running SunTools or SunView, with a few lucky(?) systems running the new-fangled OpenWindows (and that's if they ran a GUI at all, many systems were CLI only) ... regardless, for the most part these GUIs were all pretty much only used to run Xclock and multiple xterms ... at least until NCSA Mosaic came around, putting a graphical interface on things like email, FTP, NNTP, and Gopher. (Sorry, kiddies, the WWW was seen as a mostly useless toy back in those days. Still is, in some ways, when you think about it.)
Sure, there was plenty of software that made use of a GUI back then, but it was all bespoke, for a particular need, or to run specific hardware, or a student project that was mostly useless. Mosaic played a large part in making general purpose GUI software a thing in the un*x world.
As for IDEs, most folks used vi or EMACS (the later is arguably better suited as an IDE; I still prefer vi). The first true modern IDE for un*x was Softbench in about 1990, but it wasn't really usable until the mid '90s (IMO, of course).