Linux theme selection causes immediate crash if gtk2 picked

[Xkeeper0]

Describe the bug
GTK2 theme selection on Linux build causes application to immediately segfault

To Reproduce
Steps to reproduce the behavior:

1. Install FCEUX from package manager (2.6.x)
2. Configure GUI Options
3. Set theme to "GTK2"
4. FCEUX saves this change to its configuration, attempts to load the theme, and immediately segfaults
5. Segfault on open by trying to use this theme

Expected behavior
FCEUX to not crash, at minimum

(please complete the following information):

• latest Linux Mint
• latest from the package manager (2.6.x)

[thor2016]

I'm able to repro this but there doesn't appear to be much I can do here. This looks like a Qt bug.