Info node `(elisp)Tool Bar'. Items are added from left to right.
ICON is the base name of a file containing the image to use. The
-function will first try to use low-color/ICON.xpm if display-color-cells
+function will first try to use low-color/ICON.xpm if `display-color-cells'
is less or equal to 256, then ICON.xpm, then ICON.pbm, and finally
ICON.xbm, using `find-image'.