... and I don't know how to fix it. In faces.el around 975 or so, there is the following code, ;; handle X specific entries (when (featurep 'x) (frob-face-property face 'font 'x-make-font-bold locale)) (when (featurep 'mswindows) (frob-face-property face 'font 'mswindows-make-font-bold locale)) When evaluating, (copy-face 'default 'bold) (make-face-bold 'bold 'global) under CYGWIN+X, the following appears to happen, o First, x-make-font-bold is called and correctly derives the bold version of the default font. The face is then changed ('global) to this font. o Second, mswindows-make-font-bold is called and derives a Windows font name of the existing font name. The face is then changed ('global) to the Windows font! The final effect is that the font-name is set to a Windows font name for display under X. If someone could suggest a way to fix this, I'll submit the patches....