As a professional 2D Animator, I can use the Xsheet and it is OK and works fine for me and probably for others.
BUT!
The Xsheet is the old way of animations, today where most screens are horizontally (HD, FULL HD, ULTRA HD, etc..)
It is much easier to work horizontally, from Left to Right instead of Up to Down.
The Xsheet usually works a bit different then any other Timeline from other 2D Animation software but basically it does the same, frames, keyframes, onion skin support etc..
If you'll take a look on TV Paint Animation and Toon Boom Harmony,
you'll notice that they have both options / modes: a Timeline and Xsheet.
They are working in perfect sync with each other so you can work in Timeline and flip to Xsheet whenever you like in your Project.
MY SUGGESTION:
Adding a TIMELINE (Left to Right based mode) as an extra feature, not instead of the Xsheet.
I'm not a programmer but if any of the developers will be able to add an extra option (panel) that will TRANSLATE exactly what the Xsheet already does,
into a Vertical based mode like in other 2D Animation software. not only it will be easier to manage and work on our screens but also!
It will be much more inviting and friendly to other newcomers to OpenToonz who are so scared from the Xsheet.
What I think is, that the developers need to SHAPE a panel and translate all the current features we already have from the Xsheet and call it TIMELINE, there is no need for specific new features to the Timeline just translate it whenever the Xsheet gets any new feature so both can work together.
What do you guys think?
Please share your opinions and if any OpenToonz developer reads this PLEASE give us some good news! :)
* Sorry about my bad English.
Here is the rough idea I put together just to visualize it, Please notice!
I made it quick so a developer will be able to IMAGINE my suggestion for a timeline, it's not fancy or accurate at all:
For full size click the image:
