prtqlr wrote:

Would it be possible to leave everything in the dialog as is but leave the Login button enabled?

We have removed this possibility as it is not clear if the site is saved or not when you click Login.
For your use case, there's Manage > Clone to New Site command (also available in context menu).
See https://winscp.net/tracker/1069

martin wrote:

You do not have to save anything. What make you believe so?
Just select File protocol, fill in Host name and User name and press Login.

This is true but consider the following usecase: a large nr of hosts with identical setup, subnet, protocol, username (even an equal passwd). Some of the hosts have been saved previously. Now i wish to login in a non-saved host which does have the same settings. So i select one of the saved and identical host, click Edit, only change the ip adress and now i would like to simply login straight away without having to save the host.

This is no longer possible with the new Edit dialog because the Login button is greyed out. This was possible with previous releases but since the UI design (which i do like btw. :)) the login button is greyed out until the host is saved.

Would it be possible to leave everything in the dialog as is but leave the Login button enabled?

You do not have to save anything. What make you believe so?

Just select File protocol, fill in Host name and User name and press Login.

See https://winscp.net/eng/docs/ui_login

Winscp is preinstalled at our school to public computers. Its annoying how I have to save my servers address before I can login. Everyone can see it that way if I forget to delete my entries.
Also changing ports to same server is annoying because of this.