Situation: I sometimes have a long extensive detailed note from which I want to extract information, summarize parts, add some stuff, re-organize and delete a lot. etc. But, I don't want to lose the original note with all the stuff most of which I'm going to delete in the new note. I want to see both notes at the same time to work on them.
My Solution: I bought Typora and that seems to work fine, but it'd be nice if this was either a feature of Joplin or a plugin. (maybe it is?) By removing the notebook pane and the note list pane, there would be plenty of room for two notes.
It could be a very nice feature, but I'm not familiar with a plugin that does that in Joplin's desktop version.
One thing you could do, is use Joplin's vscode extension. It gives you seamless access to Joplin's database, from within VS Code. Since VS Code supports a split view of 2 editors (or even more), you may open and edit multiple notes in parallel.
I think that the VS Code extension is awesome, but if you only need sporadic 2-note editing you could achieve the same result by setting VS Code as your external editor, and opening the two notes in the external editor at the same time. As long as Joplin listens to updates that are made externally to both notes, modifications done on either editing pane will transfer back to Joplin's database.
I suppose this can be done with any external editor that can open multiple notes, either in a single window or multiple ones side by side (alternatively, use Joplin for one note, and the external editor for the other one). Maybe that's exactly how you use Typora too.
I use the wonderful plugin Rich Markdown, which makes the dual pane just a pain. So I have the regular markdown pane or the preview pane. Then I copy the note to Typora, so I have a copy there. Then I use Typora to fix everything and when I've got it the way I want it, I switch Typora to the the Code view and copy it and paste it into a new note in Joplin. Now I've got all the background information and also something that someone else might want to read.
It works. But, since I don't use the dual pane view at all, I think it'd be neat to have the ability to put a new note in a second pane.
Wouldn't it better if Joplin allowed a popout into a new window?
Seems the simplest solution
Is this the same topic ? Having a pop-out window of a note isn't the same as a second instance of the client.
1 client just allowing the editor to be detached .. open 2 notes then tile them for side by side comparison.
The simpler solution would be to allow to open two Joplin windows/instances, and to copy the "original note" to a "derived note". No real need for any kind of plugin.