This seems to be the return of bug 113714, which was fixed a couple months back by Miklos. Steps are the same: - Switch to default rendering. - Start Writer. - Move mouse over main menu. => The menu flickers. Occurs with 6.4.0.0.alpha0+ (0fb2927a8fe06e6c3255544b8e4c4c9c0f5a67d3, 2019-08-27_22:13:47) / Windows 7. No flicker in 6.4.0.0.alpha0+ (d3d13140f0036c53aa74820b41acfeffa3572168, 2019-08-14_12:05:15). => regression I'm assuming that only Windows is affected, just like with the original bug, but I haven't checked.
However, it doesn't occur with a fresh master debug build (2bd8e41a0fc10974f81695c1b2e32dc07c569d97). Maybe it's gone? Let's close tentatively, will recheck with a newer daily build