Latest master has the buttons on the document save dialog swapped, so if you create e.g. a new Writer doc, type in some characters and press ^W, then "right arrow, then Enter" no longer means "don't save". Bibisect says the range is a148fe149c7af1995fd2aaab0a6e52242509b993..41d90d6c7c41df781ecaf7745872f20abd7e52a9, likely 6c80a8fe89fadf9a2c7260a09c037a09462f53d1.
Created attachment 120520 [details] Good / old output.
Created attachment 120521 [details] Bad / new output.
is_kde5_desktop() in vcl returns true if version is not 5, that's how kde4 gets detected as kde5.
Miklos Vajna committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=8f6ecf15644b641f729c24822fcb6bb29617ef57 tdf#95795 vcl: fix KDE5 desktop detection It will be available in 5.1.0. The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.