Steven,
Thanks for the reply.
I probably misspoke (confused and low level of English).
I try again!

When a Juicebox gallery is embedded as Full Browser and fills 100% x 100% of the browser window, the only user interface is the Juicebox gallery's one. In this case (e.g. using the html page created by Juicebox Builder Pro), there is no Close Gallery button (that is normal) and the natural way to leave this gallery is the top left Back button (icon or text). Is this correct?
The Back button allows either to go back to the previous page (history.back method by default) or to specify an url (homepage for example). Is this correct?

Using a Juicebox gallery page embedded as Full Browser, I wish the user to be able to :
- return to the previous page when the gallery page is accessed from the site where it is located,
- access the home page of the site when the gallery page is accessed from a search engine or an external link.
To do that, I use the Back button icon to return to the previous page and the Gallery Title to access the home page.
When the Gallery Title HAlign is left (that's what I wish), the gallery title overlaps with the Back button icon and the only way to avoid that is to use spaces to shift the gallery title. I've done that but it's a little tricky and generates some problems (e.g. in mobile ssm mode, the Galerie Title is not on the true left of the page).

So my request is two Back buttons : a previous page button and a home page button.

Best regards.

The Juicebox Full Browser mode requires two return buttons: a previous page button and a home page button.

In Full Browser mode, whose interest is to leave as much space as possible for images, the interface of the site where the gallery is located disappears and the Juicebox interface should allow the following two features:
- return to the previous page (by accessing the gallery from the site where it is located),
- access the home page of the site (when the gallery is accessed from a search engine or an external link).
The BackButton can be used to meet either of these needs, but not both! And if a hijacked use of the gallery title can fill this gap (add a link and use   to avoid that the gallery title overlaps with the home page button icon!), a second button would really be more appropriate.

My request, concerning the future features of Juicebox: a previous page button and a homepage button.

Nice soft, nice support.
Thanks a lot Steven.
Last question, for now : the "of" refers to which button ?
Best regards.