Black XTerm borders
How do I disable the black borders XTerm/Rxvt/etc. has?
XTerms and other terminal emulators and programs with a size granularity
greater than one pixel, do not usually exactly fit into Ion's frames.
Therefore some extra space is left around them. As all the stock styles
have black frame background colour, this border is black. It should not
be a problem with black-backgrounded terminal emulators, but if you use
some other background colour in your terminal emulators, just change
Ion's colour scheme to use another colour. Alternatively, you could set
the ignore_resizeinc winprop to true, as by the glorious
ICCCM, Ion does not have to respect this size granularity. Unfortunately,
XTerm at least handles this particularly badly: instead of adding its own
borders of the right colour, it thinks it has extra character cells. But
these are too small to display the characters fully. No, it is not possible
(reliably enough) for Ion to find out the background colour of the terminal
window.