This request has been added to the tracker:
https://winscp.net/tracker/1642

Though note that you can use Duplicate Session command to open the current session in new tab or window (when holding down Shift key) and then you can open your desired (sub)folder there.

For two remote panels, see:
https://winscp.net/tracker/365

I'd like to request that feature as well.
If not in a new window how about an option to 'replace' the local browser with a remote browser.
This way it would be possible to iew two different paths of the same remote location at the very same moment in time. I'm often handing out course materials to students in the way that I hand out a link to my server, but just once.
I the keep two folder on the server and move materil from one location to the other depending on the course progress or as needed. Effectively I'm moving/copying files from one folder to another on the same remote location. Certainly, there would be more ellegant ways, but it's simple and rather 'fool-proof'.

With this in mind it would be truly handy to have two remote windows of the same remote location but pointing to different paths.

If that would be possible to implement, it would be a nice addition, at least to me and maybe others as well.

Best regards,
RaEyE

Thanks for your suggestion.
Will see if more people ask for this.

I am using the Explorer-style UI, and I would often like to have a context menu option to "open folder in new window".