Then I must be doing something wrong. Here is when I am trying under CYGWIN+X, % uname -a CYGWIN_NT-4.0 SMITHERS 20.1 (0.3/1/1) 1998-12-3 20:39:18 i686 unknown % xemacs -vanilla M-x debug-on-entry mswindows-make-font-bold M-: (make-face-bold 'bold (frame-device)) At the bottom of this message are the backtraces from entering and exiting the function. Notice that mswindows-make-font-bold is given an X font and returns a Windows font. This font is then "used" on the X device. Oops. Entering: * mswindows-make-font-bold(#<font-instance "-*-Courier-bold-R-*-*-*-140-75-75-*-*-ISO8859-1" on #<x-device on "127.0.0.1:0.0" 0x1e37> 0x40000e 0x1e65> #<x-device on "127.0.0.1:0.0" 0x1e37>) frob-face-property(bold font mswindows-make-font-bold #<x-device on "127.0.0.1:0.0" 0x1e37>) #<compiled-function nil "...(26)" [featurep x frob-face-property face font x-make-font-bold locale mswindows mswindows-make-font-bold] 5>() frob-face-font-2(bold #<x-device on "127.0.0.1:0.0" 0x1e37> default bold #<compiled-function nil "...(12)" [featurep tty set-face-highlight-p face t locale] 5> #<compiled-function nil "...(26)" [featurep x frob-face-property face font x-make-font-bold locale mswindows mswindows-make-font-bold] 5> (([default] . [bold]) ([bold] . t) ([italic] . [bold-italic]) ([bold-italic] . t))) make-face-bold(bold #<x-device on "127.0.0.1:0.0" 0x1e37>) eval((make-face-bold (quote bold) (frame-device))) #<compiled-function (expression &optional eval-expression-insert-value) "...(18)" [eval expression values prin1 eval-expression-insert-value t] 3 712083 (list (read-from-minibuffer "Eval: " nil read-expression-map t ...) current-prefix-arg)>((make-face-bold (quote bold) (frame-device)) nil) call-interactively(eval-expression) Return value: #<font-instance "Courier New:Bold:10::Western" on #<x-device on "127.0.0.1:0.0" 0x1e37> 0x40007d 0x258f> mswindows-make-font-bold(#<font-instance "-*-Courier-bold-R-*-*-*-140-75-75-*-*-ISO8859-1" on #<x-device on "127.0.0.1:0.0" 0x1e37> 0x40000e 0x1e65> #<x-device on "127.0.0.1:0.0" 0x1e37>) frob-face-property(bold font mswindows-make-font-bold #<x-device on "127.0.0.1:0.0" 0x1e37>) * #<compiled-function nil "...(26)" [featurep x frob-face-property face font x-make-font-bold locale mswindows mswindows-make-font-bold] 5>() frob-face-font-2(bold #<x-device on "127.0.0.1:0.0" 0x1e37> default bold #<compiled-function nil "...(12)" [featurep tty set-face-highlight-p face t locale] 5> #<compiled-function nil "...(26)" [featurep x frob-face-property face font x-make-font-bold locale mswindows mswindows-make-font-bold] 5> (([default] . [bold]) ([bold] . t) ([italic] . [bold-italic]) ([bold-italic] . t))) make-face-bold(bold #<x-device on "127.0.0.1:0.0" 0x1e37>) eval((make-face-bold (quote bold) (frame-device))) #<compiled-function (expression &optional eval-expression-insert-value) "...(18)" [eval expression values prin1 eval-expression-insert-value t] 3 712083 (list (read-from-minibuffer "Eval: " nil read-expression-map t ...) current-prefix-arg)>((make-face-bold (quote bold) (frame-device)) nil) call-interactively(eval-expression)