Yes, am busy with 2.8.18, the 2.9 versions of gimp I have all without a Python Konsole and therefore yet not really interesting for me ...

Difficult task: to change plugins usable both versions 2.8 and 2.9 (as you did already) without change.
OK, one can check, I think, in an plugin with what version of Gimp it is called.

If you like we could privately talk about the 'tricks' used in Araknes guide-lab ...
Several possibilities, via mail of this forum, via real email or via a private WIKI on my website ...
If interesting for you, let me know

Hi, my guidlab with Simple path shapes and random patterns used
got in a 2000 x 2000 time-, maybe too memory-problems though not (yet) crashed.

Probably I have to flatten the image now and then and maybe remove the used vectors ??!!

This version was not planned (only based on GTK - but it really is no longer a kindergarten ,
I hope that Peter will help me - after learning the basics gtk ).

Rel 1.0 FR (final release?):
- repair error (Don't stroke all layer) for Stroke Path (using SVG method)
- add shapes "Runded Rectangle", WAVE: "Sine", "Triangle", "Square" created by Jonathan Stipe 2004-2006 - necessary script-fu Shape-path.scm
- add shapes "Spirals" created by Samj (Des_spirales.scm 2013 http://samjcreations.blogspot.ca/)- necessary script-fu Shape-path.scm
- add Fill "With Foreground" and "With Background"
- add Stroke "With active brush and foreground color" (for MyPaint Brush in Gimp 2.9)
- add a separate option (Color and Line Width) for "Stroke Path (using SVG method).

Plugin Simple path shapes.py 1.0 FR for GIMP 2.8 and 2.9 in the first post.

How about a Ice cream Waffle cone addition to the shapes? Would that be possible?

Practically You can design any shape - example: Wilber and Recycle bin (only connecting points).
If You give an example of the pattern - I can try ...

MQ, I am just a beginner in gtk UI's ... used and learned a great deal from Araknes guide-lab , that author we should try to contact and start HERE(?) a new thread starting very easy ...
Telling over call-backs, how actions are triggered and the like. Where to get eventually special help, may talking together of what in pygtk.org/tutorial.html is to be learned.
AND what to do to START using it in Gimp ... There should be a lot of people knowing a lot of gtk ... but we want it for Gimp, don't we?

For myself I have a "ChangemeTemplate.py" with the idea to replace the name of the py-file into something meaningful and in the content everywhere Changeme by what would tell a reader the content is for ... .

And what is really, I think, the drawui from guide-lab, makes using gtk very much comfortable.
Sliders, check boxes etc. are, with a tool like that, very very easy.

Let me know ;-) ...
Greets
Peter

MareroQ how about an concentric line shape?
https://www.shutterstock.com/search/concentric+lines

Already doable with path-inbetweener....

You beat me to it. I was just testing that, because I thought I had done that before.

Not for 2.9

Here's the example shape:

Works excellent in 2.9. However i did have to shorten the dialog widget a bit.
To do that i just removed most of the SamJ Spiral notes. And some of the title blurb. Now i can see the bottom two buttons.

Hack
As you can see my screen grabber grabbed what it could from the dialog window.

2.9 doesn't exist

@ mackenzieh - add TEST - Ice cream Waffle (if I have to change something - attach a sketch path)
@ Rod - no longer use gimpfu3 ?. Not everyone wants - so I Shrunk the menu ("Resize layer" only interactive).
@ Peter - a new thread for GTK is a good idea. Does it start?

I use the gimp-fu.py from Bytes and Pixels in GIMP-2.8. It will not work in GIMP-2.9

For me gimpfu version Jazzon http://gimpchat.com/viewtopic.php?f=9&t=13714 in Gimp 2.9.5 Win 32 bit It works perfectly (for PF_SLIDER and PF_SPINNER).

Thanks MareroQ, That works excellent! I didn't know this would work in GIMP-2.9 versions. Pretty cool.
Thank you also Jazzon, wherever you are.

I also got Bytes n Pixels "Word Art" plug-in to function.

GIMP-2.9.5 (Samj 32 bit and 64 bit version)