I've never changed my cursor this way before, but if that didn't work maybe you could try adding the whiteglass folder from /usr/share/icons to ~/.icons in your home. It is because you are specifying the theme for this particular user (using the config file in your user directory) so I suppose you'd have to have the cursor theme installed in that users dir too.

I'm not sure about this, but hey you could try.

I miswrote the ~/.Xdefaults file but I fixed it and now I got a new pretty glass pointer
Thank you anyway

so what should be put in .Xdefaults?

It sould be "Xcursor.theme: whiteglass" and i wrote "!Xcursor.theme: whiteglass". Stupid error

You can also use pointers that you got from sites like kde-look by installing the theme directory in /usr/share/icons/ and then making a dir called "default" (in /usr/share/icons) with a file called index.theme with following lines:

[Icon Theme]
Inherits=theme-directory-name

I ended up knowing how to do the pointer change without using GNOME through an howto I read.
If you want to apply this pointer changing only to you then you do the above at ~/.icons i think.

I hope It works