I installed parrot sec kde version 4.9 today, and i have the same problem, I just made the following changes and the problem was solved:
applications > settings > system settings
and in system settings window:
on the “application style” settings i chose breeze for both GTK2 and GTK3 themes, and i chose the “dejavu serif” for font.
Also for icon themes i selected breeze too.
I had the same problem, what worked for me is getting all my updates complete first, and setting everything display wise to default and rebooting the system. It may take time but eventually worked out. Here is the link to the thread: