Code review comment for lp:~fourdollars/unity-greeter/add-hidpi-support

The problem with this branch is the hack calling xwininfo from the the greeter before starting. This is risky because:
- We're calling a relatively complicated shell script from inside an executable (very hard to understand)
- We're blocking startup for this to complete (if something goes wrong we have no UI)

The changes without this hack will be accepted, then it might be easier to do a second MP to solve the race condition.