PyxelEditor broken ui
Here is screenshot:

![obraz](https://user-images.githubusercontent.com/42244756/48858980-2464fc80-edbd-11e8-9082-a74e77f3dde5.png)
EDIT:
 - **Desktop:**
PC: Windows 10 Pro x64
RAM: 8GB
GPU: AMD R9 380 4GB
PYTHON: 3.6, 3.7.1
GLFW: 1.7.0
PyOpenGL: 3.1.1a1