It seems that the text area of some combo boxes over-renders the black drop-down surround when refreshing the contents; I guess some rendercontext / GL rendering / clipping issue. This is when using OpenGL on Windows. Picture attached.
Created attachment 118499 [details] combo box Launch calc, and then click around several cells - as you move the combo entry refreshes with this unfortunate effect.
Can't reproduce in a couple of days old build, of d48b2477aa6c768761ed9b369196b0bcd9a5bc21 .
Ah, now when I look again, I do see it, sorry. I must have run without OpenGL after all.
Tor Lillqvist committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=edbe61b671bc4c384be914099ee8bcdfd8491f3a tdf#93991: One pixel here or there, who is counting? It will be available in 5.2.0. 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.
Tor Lillqvist committed a patch related to this issue. It has been pushed to "libreoffice-5-1": http://cgit.freedesktop.org/libreoffice/core/commit/?id=ce12f0396d27b4119826bee9c30a24af9c9eb33d&h=libreoffice-5-1 tdf#93991: One pixel here or there, who is counting? It will be available in 5.1.0.1. 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.
Closing - thanks Tor ! =)