In firefox 1.5 the yahoo mail pull down menus (such as mark -> mark as
unread) are showing up see-thru so they are hard to read. My father
(XP HE) noticed this on his machine after trying to set accessibility
settings "or something" on his machine. I've tried completely
uninstalling firefox- (uninstall & deleting the directory ) Also I set
the fonts back to normal size. I scrubbed his registry, checked for
viruses. No joy. Works better in IE. Any ideas? Something with java
script?

Good day Dandanroonie,
I'm using Firefox and my Yahoo pull-down menus are quite solid. If
updating your Javascript to the latest version won't do it, try and
see if any of your settings is affecting the display of pull-down
menus.

Could you please try changing the theme of FireFox? It can be done by
moving to the TOOLS menu -> Themes option.

In my browser, the list box (for Mark option) does not show the
DropDown arrow, i.e. the list box looks like a normal Button, but when
you click on it, it shows the options clearly. It could be because of
the theme that you are using.
Kindly check that and let me know if it works.