Selecting OpenGL interface EGL fixed the menu drop-down problem, so all the programs I use operate OK, but with menu buttons grey instead of usual colour. Ths bug the same as reported in https://bugs.launchpad.net/ubuntu/+source/okular/+bug/1782132
Selecting OpenGL interface EGL fixed the menu drop-down problem, so all the programs I use operate OK, but with menu buttons grey instead of usual colour. Ths bug the same as reported in https:/ /bugs.launchpad .net/ubuntu/ +source/ okular/ +bug/1782132