I can confirm it the black elements.
But here on my computer there also are some artefacts with checkboxes (checked and unchecked).
The only themes without this problems are Green-submarine, Blue-submarine and the two contrast-themes.
Please see my screenshot.
Using Ubuntu MATE 15.10, 64 bit and LibreOffice Version: 5.0.5.2
I can confirm it the black elements.
But here on my computer there also are some artefacts with checkboxes (checked and unchecked).
The only themes without this problems are Green-submarine, Blue-submarine and the two contrast-themes.
Please see my screenshot.
Using Ubuntu MATE 15.10, 64 bit and LibreOffice Version: 5.0.5.2