When using the tabbed interface (View | Theme Settings), you can open multiple tab groups in order to display information side by side in the main application window. Tab groups can be opened either vertically or horizontally.
To open multiple tab groups
Alternatively, you can drag a tab to the far right or bottom to create a new tab group.
When you are done with your comparison, you can close the tab or drag it back to the original tab group to return to your previous display mode.