Is it planned to allow each window to have its own logon/session independent of others? I'm frequently developing against more than one schema.

We do not have any plans for this at the moment. Multiple simultaneous connections require that you start multiple Plyxon instances.

I am voting for this feature as well. I frequently have multiple schema open at a time.
Allround spoiled us with PL/SQL Dev features and omitting any would feel like a downgrade

I've always been scared of this feature, and do not like that it is (was?) on by default in pl/sql developer; It makes it easy to do things in the wrong schema.
I've always asked my developers to ensure that they pick the "Dual Session" option
Please make sure it is off by default, at least.

On a related note: Doesn't seem to be possible to color the connection window anymore.
I see I can color the connection icon in the Connections tab, but there is nothing that shows the color for the currently open connection.
It would be useful if you used that color in the tabs and/or in the titlebar
( I do like the wildcarded coloring in pl/sql developer, but I guess it makes sense to only have one way to set the color )

Btw; I see there is a very faint gray shadow behind the currently open connection in the connections tab.
This coloring is not all that useful for making sure I know which connection is open, since it is only visible when the connection tab is open, but as long as you have it, it should be more prominent.