On what grounds? Do they have a patent on spreadsheet-looking interfaces? It leaves a bit of a bad taste IMO to blatantly copy a startup that’s working its ass

On what grounds? Do they have a patent on spreadsheet-looking interfaces? It leaves a bit of a bad taste IMO to blatantly copy a startup that’s working its ass off to create a good product and then releasing it as open source, but I have a hard time imagining you can make this legal. Not a lawyer though.