Anim_picker: Expand auto opacity feature to allow click passthrough

[RafaelVillar]

Hello everyone.

The idea is that when you enable "Auto Opacity" button on the anim_picker, the ui becomes transparent but also allows you to interact with anything underneath/behind the UI.

This would allow you to interact with Maya, its viewports as if the UI were not there. When you hold Shift and hover over the UI, it will then become interactive/visible.

Here is an example of it in action.

And in case the UI becomes 'stuck' in transparency, when you disable the feature from the mgear > anim picker menu, it will flush the anim picker gui back to normal. Like so.

Testing will need to be done to ensure that the idea, feature, and current implementation are stable and open enough to work in a variety of studio environments.