Now when we got to the stage w v5 with all nice looking sidebars and layout possibilities, would it make sense to bring up a feature I really missed since long? Mentioned long time ago actually....
Having the possibility to re-arrange tabs also in the explorer. Just dragging and dropping them to their new position. For small systems with a few tabs this would not be so beneficial. If you on the other hand have a lot of tabs, like in the example below, it would be a more efficient way, you would not have to click on arrows at the top, just use the slider in the explorer to move up and down. Would love to see that!
As an alternative, I created myself a flow stack panel:

What it does is keep track of the flow tabs I've opened recently. It's stack since when a tab is opened for the first time, it's placed on the top of the stack.
In the animation, the overview of 50 flow tabs in the explorer becomes unwieldy, so the stack keeps track of the recently opened tabs. So before starting some task, I clear the stack and then begin working. Once I've identified all the tabs needed, I switch to the stack and toggle between the tabs I've viewed.
When I click on a flow in the stack, the previous flow tab is highlighted in blue - allowing me to toggle between the last two flows easily.
This is a workaround I came up with to manage my innumerable flows and one that I prefer since it also provides a focus on a subset of flows without having to hide flows in the browser.
So good, so handy, really like it, a perfect solution!
As you say, if have many tabs, it is currrently hard to re-arrange them. Especially if you then create a new one that by default is added at the end and would like it to appear as the first. The shift-click area in between existing tabs is very narrow, makes it sensitive and many times the new tab appears at the end anyway
With a great help from AI I created a cool tab manager....allows me to change tab orders and even change the name of them
@krambriw to the original request, yes, reordering via the explorer would be super helpful.
If anyone wanted to contribute to help make that happen, it would be most welcome.
Using AI to generate your own custom local solution is super powerful; just remember it can also help you make contributions back to the core... 
Yes, it is like magic!! I now have npm installable versions for Node-RED v4 & v5. Both are working really good. Changes made are reflected correctly; either directly changing tab position in the NR editor or in the tab manager side bar works as expected.
Just need to understand how to publish on npm....maybe I should just upload zip's here with a readme to start?