Like David, I downgraded the mesa packages in order for the problem to disapear. The package system needed the old libllvm library (unfortunately, I purged it with "sudo apt autoremove" before) so my command line for this downgrade/fix was
sudo dpkg -i \ libllvm5.0_5.0-3~16.04.1_amd64.deb \ libllvm5.0_5.0-3~16.04.1_i386.deb \ libgbm1_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libwayland-egl1-mesa_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libegl1-mesa_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libgl1-mesa-dri_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libgl1-mesa-dri_17.2.8-0ubuntu0~16.04.1_i386.deb \ mesa-vdpau-drivers_17.2.8-0ubuntu0~16.04.1_amd64.deb
now the menus and buttons look normally
Like David, I downgraded the mesa packages in order for the problem to disapear. The package system needed the old libllvm library (unfortunately, I purged it with "sudo apt autoremove" before) so my command line for this downgrade/fix was
sudo dpkg -i \ 0_5.0-3~ 16.04.1_ amd64.deb \ 0_5.0-3~ 16.04.1_ i386.deb \ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb \ egl1-mesa_ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb \ mesa_17. 2.8-0ubuntu0~ 16.04.1_ amd64.deb \ mesa-dri_ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb \ mesa-dri_ 17.2.8- 0ubuntu0~ 16.04.1_ i386.deb \ drivers_ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb
libllvm5.
libllvm5.
libgbm1_
libwayland-
libegl1-
libgl1-
libgl1-
mesa-vdpau-
now the menus and buttons look normally