This theme changes the following images:
[ul][li]Standard File Display Image[/li]
[li]Standard Folder Tree Image[/li]
[li]Standard Folder Tabs Image[/li]
[li]Standard Toolbar Image[/li]
[li]Standard Status Bar Image[/li]
[li]Standard Viewer Pane Image[/li]
[li]Standard Contacts List Image[/li][/ul]
If you've changed your toolbars and other elements to use other/custom images then the theme won't affect them.
The FAQ Understand and Configure Background Images is worth reading if you're not familiar with how the image config works.
Themes will change which files are used in the list at the top (the list of named images and corresponding files); it won't change the bottom part (or your toolbars) (i.e. which named image is displayed where).