The lower-case "m" in DejaVu Sans Mono 9 loses its right-most vertical line. For example, I'll attach screenshots from Vim 7.0 running under KDE on Fedora Core 5 with anti-aliasing turned on. The first one is right after I've typed the characters shown; the second is after covering the window and forcing it to repaint; while the third shows that, when I type some more into the window, the newly-typed characters still miss the vertical bar, while the old ones look fine. I have similar symptoms with "konsole" running on the same machine.
Created attachment 6134 [details] vim screenshot, immediately after typing
Created attachment 6135 [details] vim screenshot, after forcing repaint
Created attachment 6136 [details] vim screenshot, typing again after repaint
The problem occurs because the "m" glyph is too wide at that size. Do you use the autohinter? If the answer is yes, then there is nothing we can do, the fix should be made in the autohinter, or in Qt, which should allow glyphs to be wider than the glyph width in monospaced fonts (Qt4 seems to be doing it right, but off course, we're still a long way from KDE4). I can only see this effect at smaller sizes (8 and 9 ppem, which is probably around font size 6 on your screen). It should be fixed at those smaller sizes, but the problem you have occurs at larger sizes, and should not happen when the hinting instructions embedded in the font are used (i.e. when you enable the bytecode interpreter from FreeType)
Thanks for pointing me in the right direction: I checked my KDE settings and found that I had set "Hinting style" to "medium" under anti-aliasing configuration (I assume that's the default, as I'd never changed it). I get the same symptoms with "slight"; with "none", the character is properly formed but very blurry, while with "full" it looks all right.
So the problem is fixed then? Odd, cause I never thought setting hinting style to full instead of medium would work. I was talking about the autohinter in Freetype, where the bytecode interpreter should be used instead (because it gives a much better result). To my knowledge, Fedora doesn't include that bytecode interpreter due to patents. To activate the bytecode interpreter you have to compile Freetype yourself (or find a good rpm for it). Anyway, as it is fixed, I guess I can resolve this into NOTOURBUG then
Mass move of freetype bugs to the new freetype product
Reopen the NOTOURBUG reports now they're correctly affected
I close this bug; it should be fixed since FreeType 2.3.3.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.