Comment 7 for bug 33144

discussion upstream about that:

"It's not Pango, not FreeType. Plain vte bug. Here are the details:

vtexft doesn't know about bold faces. When it wants to draw something in bold,
it redraws it again shifted one pixel to the right. Of course that means it
may be overlapping the next box, which it is in the example.

Now following the example here, if the chars 'mp' are redrawn together, you see
them overlapping, but when later the 'p' is redrawn only, it clears its box and
draws a p, which means the part of m overlappint p's box is cleared...

Not sure how to fix this. Widening the boxes by one pixel is not that
appealing.
...
> why is the "p" redraw when you enter the "h"?
...
Heh, *just in case*. Because ph may be a wide character. So instead of
checking whether it needs t redraw p, it simply does that all the time. It's
one of the things I'm working on currently in vte: to remove excess redraws.
But that doesn't really solve the entire problem. It will still show up in
other situations."