Missing icons and buttons on main GUI window (Ubuntu)

With current and previous versions of RPCS3, the icons for the games and toolbar buttons do not appear in the main GUI window in Ubuntu 16.04. (See screenshot)



The terminal window in Ubuntu is reporting the following output:
libpng warning: Application built with libpng-1.2.54 but running with 1.6.21

Video driver: (nvidia-381) 381.22-0ubuntu0~gpu16.04.2
CPU: AMD FX-8300

Attached should be the RPCS3.log and a build output.

To work around this, I installed new dependencies:

libpng16-dev libpng16-devtools


Then built with flag option:

cmake CMakeLists.txt -DUSE_SYSTEM_LIBPNG=ON

Screenshot: