Looking for a "custom" script editor

[NewBeginnings]

I started with python in a 3D-application (Autodesk Maya), and I fell in love with its script editor. It looks like this:


It executes code when the right return-key is pressed. If no text is selected, it will execute all of the code. Else if something is selected, it will execute the selected code.


The reason I can't just continue using the 3D-application to work with python in is that it only works with python 2.7. I'm in the process of moving towards python 3.7, so I need an alternative. All of the standard editors feels "clunky" to me, and I don't really need anything other than simple input/output in my editor.


Here's what I'm looking for (in chronological order):

1. Always executes selected code only (if no selection, everything is executed)
   
2. Option to specify hotkey (for executing code)
   
3. Clean design, I don't need (or want) anything other than editor & output
   
4. Portable
   

It's basically just a slick wrapper, is there anything like this out there? I'm sure there is, but I haven't been able to find one. Any tips would be greatly appreciated :)