Comment 2 for bug 1294578

Thanks for the detailed description Eleni!

I see a few issues with the approch there though/I'm not sure to fully understand, so I've some comments/questions

* do you suggest having changes to the factors done for you the first time the user open the panel ? That seems like a wrong/confusing behaviour for several reasons:
- the session would look wrong until the user goes to that panel
- if things change it's not obvious why
- it's not obvious how to undo what happen

* do we really need the "by monitor" logic? that seems over complicated.

Let's say I've a docked laptop with an external monitor. The checkbox is checked for the laptop screen. I select the external one, it's display as uncheck ... but the GTK UI are scaled still, right?

What's the goal, having the scaling parameters calculated based on the geometry of one of the screens? If so wouldn't it make sense to have a checkbox "scaling on/off" and a combo "monitor to base the scaling value on"?

* how does that play with the accessibility setting for "big text" that sets the text scaling to 1.25? it seems like those settings are going to conflict

I think I would rather prefer to see a much simpler approch. Having 1 checkbox "scale UI on all monitors" and have it set the GTK scale to 2 and the text scale to an appropriate value. Even that is going to have weird interaction on the text factor between accessibility and hidpi though...