double quotes, e.g., @samp{"red"}. RGB triplets should be written
without double quotes, e.g., @samp{#ff0000}. GTK-style RGB triplets
have the form @w{@code{@{ @var{r}, @var{g}, @var{b} @}}}, where
-@var{r}, @var{g} and @var{b} are either integers in the range 0-65535
-or floats in the range 0.0-1.0.
+@var{r}, @var{g} and @var{b} are either integers in the range 0--65535
+or floats in the range 0.0--1.0.