The Display preferences page and its subpages contain options to change the appearance of foobar2000.
User Interface Module
This option selects the active user interface module. In a fresh foobar2000 install, there's only one option to choose from: Default User Interface. Other available interfaces are provided by third party components.
Controls the behavior of selection viewers (Album Art Viewer and Selection Properties in Default User Interface).
Allows you to customize the way foobar2000 searches for album art to display.
The following subpages are present if you have Columns UI (foo_ui_columns) installed. Columns UI is a third party component.