elementary_tests.exe: Slideshow stops showing images after a while

[Coquinho]

Current behavior

After showing images for a while, some of then start to show as black screens, like they stopped to load correctly.

Expected behavior

To show every image, don't matter how much time the application is on.

Steps to Reproduce

1. Run elementary_test.exe
2. Open Slideshow
3. Here you can do at different forms like pressing next/previous many times or reducing the time to 1 and letting it run by itself. The transition effect and fullscreen didn't seem to influence anything.