This is the worst text based editor of any kind on the planet. Why? No matter where you are in the document as soon as you press ANY key, the entire document scrolls so that your cursor is the last line of the view port. Not only is this jarring, but it makes it impossible to see what is below where you are typing. So you scroll up to type the first letter, scroll up to type the next letter, scroll type, scroll type, scroll type.... one... letter... at... a... time. This "auto scroll on type" has to be fixed to make this even marginally usable.
This issue is compounded SIGNIFICANTLY if you are still in the trial period because the black banner completely covers the last several line of the view port. So the view port max height should be changed to keep it from going below the top of the banner box if someone is in the trial period.
This is all but impossible to use in it's current state. It needs fixed ASAP.
Also, the editor is not wide enough. This causes a lot of needless line wraps that make the code look jumbled and messy. There is a ton of wasted space on either side of it that could be better utilized as part of the editor. it doesn't need to be 100% width, but it could be easily doubled to make everything look better and be more usable.
Both issues are depicted in the screen shot below.
EDIT: One more thing, make the Toolbar (the part with the "Save" button and "Actions" drop down sticky. This way if you are editing something at the very bottom of the document, you are having to constantly scroll back up to preview, and back down to change soemething and back up again...etc.