Ah true. I couldn't reproduce it before because it doesn't happen with all fonts; I'm using Fixedsys Excelsior. Switching to plain Fixedsys, I can reproduce the bug. Oddly enough, Excelsior v3 is the only font among the ones I tried that does not exhibit this problem (Excelsior v2 does).
However, there is another serious problem after echoing that line using Excelsior (v3): when the window is resized by dragging the right edge to the left, as soon as the text wraps, mirc freezes, consuming 100% CPU.
