When creating or enabling a UIWidget in a hierarchy that doesn't contain a UIRoot, it creates one and re-parents the hierarchy under it. This causes problems. We don't use a UIRoot because we do some more complicated scaling the results in pixel perfect UIs on a couple target devices, and then scales to fit based on both width and height on other devices. We also have a couple of stand alone colliders that intercept and process events. I've added UIWidgets to these colliders so it gets sorted correctly for events. The problem is, when the UIWidgets on these colliders are enabled (i.e. when the GameObject is enabled), they basically destroy hierarchy. There are two outcomes. 1) The widget doesn't find a UIRoot on the root object, so it creates a new UI and re-parents the current hierarchy under it. Problem is, the re-parenting resets all layers in the game to Default. We use a couple layers for masking events and this breaks all interaction. 2) The widget finds a disabled UIRoot on the root object and resets it's scale to 1,1,1 for whatever reason. Our custom scaling script was originally on the root object (effectively replacing UIRoot with a custom one) so this object has a specific scale set. Resetting the scale blows up the game.
I ended up setting up the hierarchy with a disabled dummy UIRoot as the root object, the GameScaler under that, then the UICamera under that. Like so:
And this doesn't break things.
