I can verify this too in both 32-bit and 64-bit versions but just the buttons. The mouse scroll wheel for zooming works fine.
Linux Mint 18.2 on Kernel 4.8.0-58. The keyboard is captured properly so I can pan the camera and I can also mouse wheel to zoom in and out but none of the buttons are captured. A Wacom Tablet has the same issue where none of the pen buttons are captured either.
This means you cannot actually quit the program as you can't click on Quit.