How NOT to show categories on main page but still keep the subcategories open?

[Cindy2010]

Hello,
Is there a way that NOT to show the categories on the center of the main page, but still keep the subcategories open on the side box?

I am trying to play around these 3 settings:

Categories - Always Show on Main Page
Main Page - Opens with Category
Categories - Always Open to Show SubCategories

Disable the first one will hide the categories in the center of the main page, but in the sidebox, the subcategories will be hidden as well. :-(

Thanks!

[Cindy2010]

Oh, by the way, how can I find the corresponding variable names for the above 3 variables? I want to search them in the code to take a close look.

Thanks!