So then it's the editbox or what? If i type ALT+0159 i can see Ÿ (Latin Captial Letter Y with diaeresis) and when i send it or echo it, it disappears. Or better it becomes a control code.
When you type Alt+0159, Windows (and not mIRC) produces the Unicode equivalent of the char from the codepage that corresponds to your current input (keyboard) language. The reason you may sometimes see a block is probably because you are not using a Unicode font (such as Arial Unicode MS or Fixedsys Excelsior): in that case, fontlinking kicks in, grabbing a symbol (glyph) from the first font it finds in your system that claims to support that character. In practice this does not always work, so sometimes you get a block. Note that this will never happen if you switch to a Unicode font.
The aforementioned behaviour of Alt+NNNN can be handy in this case. For example, if your old scripts use a hardcoded char 159, you can simply delete it and hit Alt+0159 in the Editor to get the Unicode version of this char.
