[Solved] OnlyOffice doesn't open in a new window anymore

Since Nextcloud 21, when opening an OnlyOffice document, it doesn’t open in a new window any more, but remains in the same window. This is very much inconvenient : if I need to open a few documents about the same project, I have for each of them to browse the entire folders path to the project from the start folder.
I haven’t found a way to change this behaviour. Is there any ?
Note : I’m not sure whether this is related to Nextcloud or OnlyOffice.

How silly : after months trying to find the solution, I find it some minutes after posting here !
Just need to uncheck the new checkbox in the admin parameters.