Summary: Per monitor scale factor
Per monitor scale factor for all user interface components. The values are stored in a dictionary where the keys are IDs of monitors and the values are the scale factors. The scale factors are not the traditional float scale factors that one might expect. Instead they are integers that need to be divided by 8 before being used as regular scale factors. That limits the number of possible scalings applied to the UI without jeopardizing flexibility (there is still enough possible scalings for all devices out there). This limiting allows for better testing since there is now only a finite number of possible scalings. The scale factor also maps directly to the grid units used in the Ubuntu UI Toolkit where one grid unit is exactly equal to 'scale factor' number of pixels.
In the array, there must be one and only one while space behind the comma(,).
Or else, the default value can't be restored