I think we can't do that yet - please create an issue on github.

Does that Krom error happen on any project? What macOS version is that? Is that using the integrated Kha version?
For multiple filters, switch between multiple render targets.

Shader debugging - not yet. Krom - yes but try to use Kode Studio's integrated version of Kha instead of a newer git version (because there were API changes).

Thanks, will have a look (but report bugs on GitHub please).

You can't run a Kha project without a khafile. Run node /some/path/make --init to create a basic Kha project (same as F1->init) , then /some/path/make html5 will work and you get your HaxeDevelop project. Or maybe do /some/path/make flash because HaxeDevelop still can only debug flash projects AFAIK. The khafile defines the structure of your project (where assets, shaders and Haxe sources are). You should also call khamake every time you add assets or shaders to your project, HaxeDevelop knows nothing about those.

Framebuffer is a Canvas - it's just a small interface containing the shared functionality of Framebuffer and Image.

Use the v17.1.x branch - the master branch is in a broken trying to merge with current vscode state.

Yes, you have to draw to an image and apply the shader afterwards. I created an example for you: https://github.com/Kha-Samples/Shader-G2
This sets a shader for G2. Alternatively you can also use G4 to apply a shader which is more flexible as you don't have to adhere to the shader inputs used by the G2 implementation - but if you're just getting started with shader programming, use the method shown here.

You can of course set the viewport (via the viewport function) but the viewport is already set up for that by default. Setting an orthogonal projection is all there is to it. You can also have a look at how Kha itself implements 2D graphics on top of 3D APIs: https://github.com/Kode/Kha/blob/master/Sources/kha/graphics4/Graphics2.hx

Yes, that's it if you want to draw two dimensional geometry using g4.