Before reinventing the wheel: does anyone know of a library that would contain something akin to radio buttons but in 2D?
I don't, though I'd be interested too.
If you can make do without a visible grid of buttons, and deduce button presses from coordinates on a plane instead, the available 2D / xy sliders + a bit of dividing/rounding could work:
https://forum.pdpatchrepo.info/topic/8656/xy-slider-controls-two-variables-a...
https://forum.pdpatchrepo.info/topic/13818/xyz-slider-3-d-slider-using-mouse...
https://forum.pdpatchrepo.info/topic/2699/xy-control
https://forum.pdpatchrepo.info/topic/10854/xy-abstraction-to-get-mouse-click...
Best, Albert.