Applying a different theme to the Portal InnerDesktop Page

Hi Everybody,

My requiremtn is that whenever i click any link in the detailed navigation panel, i should be able to change the theme in the inner desktop page only and not to the whole desktop on the basis of the link clicked. Means if i click one link in the detailed navigation panel, i should be able to open a new page in the content area with new theme applied and if i click some other link in the navigation panel some other theme should get applied to the page which will appear in the content area. Its really urgent..kindly suggest some solution.

A suitable answer gets entitled for full points.

Thanks in advance.

Regards,

Sarabjeet Singh.