Incorrect rendering of unicode characters

[sedwards2009]

The demo here https://github.com/yaronn/blessed-contrib uses (and abuses) all sorts of unicode characters in its dashboard and charts. As we can see in this screenshot below, Extratrem doesn't correctly render it.

The main problem seems to be the widths of the characters which are not monospace even though Im using a good monospace font. Extraterm should handle this better.

[ashb]

I'm having issues where some emoji characters are being clipped: U+2717/✗ for instance:

Compare to the same thing in Konsole (same font, but maybe at different size):

I understand this is a tricky problem - is there anything I can tweak?

Related might be a similar clipping problem with italic chars: