better HiDPI setting location and default

[Bender72]

I lately installed Mint 19.0 Cinnamon and 19.1 MATE on two machines with a 4k display and in both cases, it was a struggle to find the HiDPI setting location.

On MATE, I couldn't find the setting in Displays, where I first thought it might reasonably belong. I also couldn't find it in Appearance, or Desktop Settings, or by searching the Control Center for "HiDPI".

Then I looked at the New features in Linux Mint 19 MATE page again and discovered that HiDPI is in Desktop Settings after all, it's just that I was scanning for the word HiDPI and the option "User Interface Scaling" with its only visible default "auto" didn't trigger the association for me.

On Cinnamon, I also need to search to find that the option is under the nondescript "General".

This behavior is doubly user unfriendly. On a 4k display at least, the default "auto" should automatically switch to HiDPI scaling. The auto should err on the side of higher scaling. Having fonts and icons that are too big is just a slight nuisance; but fonts and icons that are microscopic make a system unusable.

The problem is compounded by the fact that the HiDPI setting is not very prominent. I think it most logically belongs in Displays, because it's essentially a function of screen resolution.

[jaymot]

+1 on this! It's very difficult to change scaling when you can't even read the menus and settings because they're so tiny. That's also very ADA-unfriendly for vision-impaired users.