I am using KDE Ubuntu and I upgraded to the newest LibreOffice 5.3. I love it, thank you for the upgrade.
In any case, the application icons that I had for LO5.2 looked very slick in the Plasma environment. But when I upgraded to 5.3, I think they reverted to an older set of icons (or probably a different distro) that are OK, but therefore don’t do justice to the amazing new release with the Ribbon UI and everything.
In fact the older icons only appear in the menu and in the taskbar, but the newer are shown in the application window. I took a screenshot, but I can’t upload it because I don’t have a reputation. =(
Let me know how to setup this icons, or if you need other information about my system. Cheers.