Since Inkscape does not seem to support leading multiple files in the same window. Each file must be loaded in a separated windows.

The problem is that each time I open a new file, it opens a new windows, and reset all the interface setting to the default. So each time I open a file, I need to set up again the docks I needs and some default parameters in that dock.

So I was wondering:

Is there a way to close a file without closing the inkscape window so that I could open another file afterward.
OR
Can I open a new file in the same window I am working in by replacing the old file withe the new one.
OR
Is there a way to save the interface's current setup so that each time I open a new window, all the docks I want would stay open.

Is there a way to save the interface's current setup so that each time I open a new window, all the docks I want would stay open.

Yes
Please go to File menu > Inkscape Preferences > Windows

Also, if you use the exact same canvas setup each time, you can alter your default.doc, so that it opens with your own particular setup. Please find instructions in this topic: viewtopic.php?f=6&t=162

I think you will find these changes make your life with Inkscape much easier, lol!

I already have configured the Default.svg and it works. But the default file does not save the docks in it. Unless I made an error. I'll make some test.

larienna wrote:But the default file does not save the docks in it

No, Inkscape does not save the state of opened (docked or floating) dialogs between session. This is an often requested feature, but not implemented:

Bug #171579 in Inkscape: “Make inkscape remember dialogs window status”

larienna wrote:Inkscape does not seem to support leading multiple files in the same window.

Yes, Inkscape is document-centric and doesn't use a shared workspace or tabbed multi-document interface - see feature requests like “Tabbed document interface for multiple documents (TDI/MDI)” or “Open several documents in the same workspace” in the bug tracker.

larienna wrote:Is there a way to close a file without closing the inkscape window so that I could open another file afterward.

Not possible - Bug #170550 in Inkscape: “open blank document on 'close'”

larienna wrote:Can I open a new file in the same window I am working in by replacing the old file withe the new one.

Not possible either. The current window is only reused when you opened a new file (from template) and didn't 'dirty' it yet.

larienna wrote:Is there a way to save the interface's current setup so that each time I open a new window, all the docks I want would stay open.

See previous comment (bug #171579)