The Canary and Dev versions recently got the ability to use Chrome Webstore themes. This is great. However, to improve the overall experience, I feel the user must be able to download multiple themes at once, and switch between them whenever he/she wants to.
Under edge://settings/appearance, a list can be included which contains the name of the current theme as well as all the themes stored by the user.
If it is not possible to provide the feature to download multiple themes at once, at least a list of links to all the previously downloaded themes can be provided so that the user can download and use them again.
This will also prove useful if the user accidentally reverts the applied theme.