DiffScreen.draw() marks wrong line as dirty when wrapping occurs

[dcoshea]

The current implementation of DiffScreen.draw() in pyte/screens.py as at 12276a8 is that it first marks the row containing the cursor as dirty and then calls Screen.draw().

However, the latter method will, if wrapping is enabled (if mo.DECAWM in self.mode), move to the next line before actually writing the character to the virtual terminal. This means that the wrong line might have been marked as dirty.

It seems to me that simply switching the order of the statements in DiffScreen.draw() would fix this issue.

[superbobry]

Thank you for reporting this. It seems that with wrapping enable the dirty line would indeed by y + 1 and not y. Do you mind submitting a PR with a unit-test for this case?

[dcoshea]

Sure, thanks!

[dcoshea]

I submitted pull request #38, hope it's ok :)