Xmir reports the phone DPI even on external monitors

[kevin gunn]

on latest image, adjust GRID_UNIT_PX to ~8 globally for unity8, all the native unity8 applications look correct when running on a Nexus 4 & attached to external monitor

install puritine, launch FF, while attached to external monitor. Scaling is incorrect (large) due to xmir dpi being based on physical phone screen - need a way to tweak/hack to make FF appear usable.

[Chris Halse Rogers (raof)]

This commit¹ in xmir git makes XMir behave like Xorg - it respects the -dpi command-line parameter, defaulting to 96DPI.

As it makes XMir behave like desktop Xorg we'll need the same compiz/toolkit/application level tweaks we currently use on the desktop to enable HiDPI mode if we want XMir displaying on the phone (or an external 4K display).

¹: https://git.launchpad.net/~xmir-team/xorg-server/+git/xmir/commit/?id=5aca7b08cd4d8c33e3a09083b0c64dabd5f89cb6

[Daniel van Vugt (vanvugt)]

Sadly, if you want mature hiDPI support then we're going to have to take Xorg out of the equation...

The fix Chris did seems like a reasonable workaround. It just removes some of the functionality I was asked to add. However it doesn't qualify as Critical (https://wiki.ubuntu.com/Bugs/Importance)