This inverts the colours of any canvases on the current page.
This extension inverts the colours of any canvases on the current tab.
Might be useful if you enjoy strange colour combinations.
Or to make a faux dark theme in DAE. DAE only updates the parts of the screen that change. So click the extension's icon (it'll probably be in the extensions menu, the jigsaw piece looking thing), then open a new tab within DAE and close it, that'll update the whole screen.