For example, if I am typing and I hit the editor current box size, instead of adding the scroll bar, expand the editor box size up to the screen view size. Only then, add the scroll bar.
This same behavior should apply when editing a question (On GitHub also does this). On this case, if the question is small enough it already fits on the text editor view area without a scroll bar, do nothing. But if the questions body is bigger than the standard text editor size, expand it up to the maximum view size, only then add a scroll bar.
As someone will probably complain, the GitHub and StackExchange websites text editor have a main difference, GitHub has a
Preview button, while StackExchange directly shows the
Preview just bellow the text editor, related to an WYSIWYG text editor.
On this case, when I say
expand the editor up to the view size, it should also consider the space taken by
WYSIWYG Preview area, and not literally expand to the full extend of the view area.
Now a problem rises when the editor text is very big and the preview area is also very big. How it should expand? For me, the text editor can expand up to
75% of the view size, while the other remaining
25% stays reserved for the preview area.
I would say it is already good size as default. If someone likes it to be bigger than
75%, should be simple enough for them to increase. If someone likes it smaller more like
50% - 50%, is also should be simple enough for them to decrease it.
I just cannot think anyone can adequately work with the text editor size with the size of
25% of the screen as it currently is, when the question text is bigger. Because you can barely see where you are on the text, and what are the other things you have. And as the preview area is fixed to only show you the top of the question, it does not make much sense to have a preview area showing up on
75% of the screen, while you are probably working on something out at the middle/end of the question text with a text editor with
25% of view size.