Expose hairlineView to be able to hide it, change background color, etc

[hipwelljo]

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Description

The new hairlineView could be exposed publicly to allow us to hide it, change its background color, etc

Attachments

[rromanchuk]

Yeah, this is problematic 46113e0

[dzenbot]

We have reverted the changes from #624 to be using UIToolbar again. This won't be possible easily, sorry.