This is the top-level container element for every thmutil Theme file. Relative path to an image file that can serve as a single source for images in the rest of the theme. This image is referenced by controls using the SourceX and SourceY attributes. Mutually exclusive with the ImageResource attribute. Identifier that references an image resource in the module for the window. This image is referenced by controls using the SourceX and SourceY attributes. Mutually exclusive with the ImageFile attribute.