How Could I Add Annotations And Highlights in PDF Files in An Xfce?

How could I add annotations and highlights in PDF files in an Xfce desktop environment?

If by “lightweight” you mean, does it use less memory out the box than most? Eeeh … it’s about average, “lighter” than some “heavier” than others. BTW, “lightweight” is a fuzzy concept anyway. Take something like Lmde as one of the lightest, install all sorts of programs into it, add extensions to make it look nicer and add more features … you’re likely to end up with a desktop which eats up just as much RAM as a “heavyweight” DE. In fact, with KDE’s recent updates t’ve optimized their memory footprint so much that an out the box KDE uses just as much memory as an out the box Xfce (within a handful of bytes). And that was historically one of the more “heavyweight” desktop environments. But as stated above, this usually matters only marginally. Seldom do you only run a desktop. The very purpose of a computer is to run actual programs, and the desktop is just a means to allow you to “point and grunt” at it so it opens the correct program. As a rule of thumb, the more “bling” the more “helpers” the more running tasks - the “heavier” some desktop is. “Lightweight” tends to mean only the actual bare necessities are left, everything else is cut away. In most cases this means the DE is much less “user friendly” for those who want the extras, it may look uglier as well. Xfce was historically a reasonable compromise between cutting out the bloat, but keeping enough to still feel adequate for most people. With things like Lmde focused on cutting ut as much as possible without making it completely useless, and KDE/Gnome adding nearly every conceivable bauble and tweak people even just suggested. Things have changed though, it’s no longer as clear cut as it was last year, never mind 10 years back. Some of the others have been in a lot more active development than Xfce has. Both moving towards it on a “lightness” aspect as well as away from it. If your “ultimate” is to have the lightest possible system, then don’t use a DE at all - run everything from a command line. With a second best alternative using a window manager instead of a full blown DE. But I can guarantee you, if you’re not willing to learn and not already experienced in those. It’s going to feel extremely irksome at best, you could even feel completely lost at worst.