I don't know of any way to change a single cursor, but I do use gnome-extra/gcursor to change
the entire theme. Probably not exactly what you want but it's a start
I've noticed that under Gnome Opera tends to ignore your cursor theme anyway. Not sure if it's a QT thing
but yeah...
Thank you both, I do not have Gnome and my WM is Fluxbox, while my wife is using KDE. As you say Opera (and FF-bin?) are compiled with static Gtk+ decorations, so changing the WM settings does not have an effect. I even tried manipulating the Xorg variable for cursors: export XCURSOR_THEME=whiteglass, but that didn't do anything either.
I know the blue glass cursor theme give some info for setting the cursor theme when you install it.
/usr/share/cursors/default/index.theme "inherits = cursor_theme)name" or something like that. sorry, I'n not on Gentoo atm.
Xcursor (mostly) follows the freedesktop.org spec for theming icons.
The default search path it uses is ~/.cursors, ~/.icons,
/usr/local/share/cursors/xorg-x11, /usr/local/share/cursors,
/usr/local/share/icons, /usr/local/share/pixmaps, /usr/share/cur-
sors/xorg-x11, /usr/share/cursors, /usr/share/pixmaps/xorg-x11,
/usr/share/icons, /usr/share/pixmaps. Within each of these directo-
ries, it searches for a directory using the theme name. Within the
theme directory, it looks for cursor files in the 'cursors' subdirec-
tory. It uses the first cursor file found along the path.
If necessary, Xcursor also looks for a "index.theme" file in each theme
directory to find inherited themes and searches along the path for
those themes as well.
If no theme is set, or if no cursor is found for the specified theme,
Xcursor checks the "default" theme.
If God has made us in his image, we have returned him the favor. - Voltaire