Can I stretch my FCP Timeline across TWO displays?

You CAN have the timeline across both displays!

There is a big trade off, though.

You’ll have to switch OFF “Displays have separate Spaces” in System Preferences->Mission Control.

That will bring back the way multiple displays worked circa OS X Mountain Lion.

You’ll lose menu bar on second display and full screen applications will just use one screen and black out the other.

WELL... Actually I could not wait and tested. It WORKS.

The whole FCP interface uses both displays. Just start in one and extend the window.

You are not wrong. You can put it on another monitor, but you can’t have it span across two monitors.

The only way I can think of displaying more timeline is to use one of those super-wide curved monitors.

As a side effect it would probably be a lot cheaper than the Apple display.

EDIT: Sorry, just seen you have spotted that option. For some reason no replies were showing when I read your question!

I haven’t actually tried this because I have no use for it and it would require a restart to test and another to go back to my usual settings.

I could test tomorrow.

Can you not drag to extend the FCP window across the two displays?

I think only by putting Safari in full screen so it’s in its own space.

There's a heck of a lot of info on curved monitors on YouTube.

https://www.youtube.com/results?search_query=curved+monitors+for+fcpx

The one from B&H shows the fantastic expansive timeline effect you can get . . . though he is using a windows PC!

Obviously as with everything there are pros and cons, one of the cons being that you need to sit at a specific (fairly close) distance to the display and be completely central.

This is presumably why curved TVs have died the death because though they may be ideal for one viewer seated centrally, most TVs are watched by family groups some of whom will be viewing off-axis.