here is a basic grid abstraction for ofelia (multitoggle.pd).
its based on the toggle from the ofelia gui abstractions.
it has three arguments for togglesize, x-number and y-number.
its possible to draw inside the grid with the mouse.
all the midi / sequencing things from the example happen inside the abstraction, it could be simplified or modified for other purposes.
ofelia_multitoggle.zip

@Jona

woah. This is really amazing. nice work.
I've never used ofelia, and I use pd mostly on a Raspberry Pi. I don't think Ofelia is available for Rpi yet.

But this is really cool. I'll try it out on my mac. Thanks for sharing.

in this version i implemented a multislider for (midi) velocity and note length. could also be nice for controlling/ visualizing synth parameters. i am sure the patch can be improved but i am happy that ofelia seems to be a good pure data solution for complex interface ideas. ofelia_multitoggle_pvl.zip

and here is a multiradio abstraction. it has the same functionality as the multislider but a different appearence.
and its based on the vradio from the ofelia gui abstractions.
ofelia_multiradio_c.zip

i changed some things in the multiradio and multitoggle abstractions. the gridcolor is now independent from the toggles. the multiradio could be useful for something like the reason matrix sequencer. could also be nice to implement some of the grid functionality: https://forum.pdpatchrepo.info/topic/11012/grid-multi-pattern-step-sequencer-abstraction
or even the game of life patch from @weightless
https://forum.pdpatchrepo.info/topic/10916/conway-s-game-of-life-implementation-with-data-structures
ofelia_multiradio_multitoggle_e.zip
edit: just seen that a big multitoggle grid needs quite a lot of cpu at the moment, perhaps there is a way to optimize it.
just a random music example for demonstration purposes: