Your comments

The total width (in terms of characters) of the two text views should be made equal to the longest line between the two views.

A stupid implementation can be filling  the last blank  line of both sides with as many spaces as max(char width left, char width right). Given that the font is monospace, now the two views will be in sync even if they have lines of different length (because the longest line with the spaces is the same length on both sides).

This last line should be somehow ignored in the comparison.

Probably better implementations are possible.

Also  it would be useful to have a option to enable text wrapping, to avoid the scrolling. Sometimes latex documents have very long single line that on the latex editor (e.g sharelatex) are wrapped, just to give a use case.

>  Also, I like to double-check the commit contents before committing.
This doesn't imply closing the index editor given that they are two separate windows, especially in a multi screen environment where all the smartgit windows can be open and visible at the same time.

I agree on the problem of multiple stale windows.