> Doesn't this solve most of that?
>
> "Being browser-based, the UI style can be modified using CSS. We're keen to add a custom theming system to allow anyone to edit the appearance!"
>
no, if there are no lines, there is no CSS to replace, the "custom" interface we can do its just replace already created assets of the interface and colors.
You'd be surprised how flexible CSS can be - you can get very creative with selectors and pseudo elements. If the editor truly is created entirely in HTML5, this will definitely be possible.
The best C3 feature I've seen yet is in that same screenshot though. Now we'll be able to copy actions as text! (Something that I really will use, though obviously not nearly enough of a feature to upgrade for.)
This got me excited as well, I wonder how far the "copy as text" extends? Is it just the action, could it be the whole event block? Very obvious learning and teaching applications for here on the forum.
But what really excites me is that it would imply a relationship between the event editor and typed text; an actual typed syntax... Which could mean that C3 might have a text based event sheet for those that prefer to type code!
EDIT//
Looking at it more closely, I really like the subtle border radius on the edges of comments and events.