Hi @Ian_Hardenburgh, Looker Support here. With regards to this specific functionality to freeze window panes, that functionality isn't currently slated for a near-term release. Looking at the above thread I see there was mention of 2018; however with that being said, our Product Team and Managers are always working in a balance between planned work and incorporating user's feedback into new design considerations.
We always appreciate hearing about new use cases where this or any other functionality can be applied. So always feel free to reach out via Discourse or via email at email@example.com.
And our outgoing Release Notes is the best place to keep up to date with new features that are released.