Menu flickers on iMac OSX 10.14.6

[saskatoonie]

When using VLC to add subtitles to video, I select from the VLC menu at the top of the screen and immediately the menu drops down and flickers rapidly. The same operating system on my MacBook Pro does not have this problem. I have tried reinstalling VLC and the OS but my iMac 27 inch computer still has this flickering problem when the menu is activated on VLC. I think it started after the latest OSX update, but I am not 100% sure. Any ideas out there?
System info: iMac (27-inch, Late 2013).  3.5 GHz Intel Core i7. 8 GB 1600 MHz DDR3. NVIDIA GeForce GTX 780M 4 GB. VLC Version 3.0.8 Vetinari (Intel 64bit)

[ePirat]

This sounds like the graphics issue discussed in other topics, for example here https://forum.videolan.org/viewtopic.php?f=12&t=150244