We've had a number of black / flickering issues in 5.0.x with OpenGL in-use. These stem from the fact that we are seeing the live rendering as it happens. A fix for that is on its way for 5.1.0 - this is a tracker bug for that.
Gerrit has a fix we're testing for this: https://gerrit.libreoffice.org/21405 Seems to handle many cases - also we've switched the background clearing to white from black; so most users will perceive much less flicker anyway =)
Michael Meeks committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=8d6c1b6981f01bbc0057234f53fd139e87a5f010 tdf#96385 - opengl: dynamically adjust priority of swap buffers. 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.
Michael Meeks committed a patch related to this issue. It has been pushed to "libreoffice-5-1": http://cgit.freedesktop.org/libreoffice/core/commit/?id=6fa1b457fc90ca92a1e8e70d4446cd5462da3158&h=libreoffice-5-1 tdf#96385 - opengl: dynamically adjust priority of swap buffers. It will be available in 5.1.1. 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.
All dependents now fixed; close for now.