Hi @André Dinis,
The problem, as you have notice is an infinite cycle, or close to it.
The reason for that is that the API that you're using, GridAPI.Styling.SetCellCssClass(...)
requires the grid to be invalidate (as you can see in line 46), so that the changes become visible. Worth notice, that the this API was not designed with your scenario in mind (as in, using it with the event updatingView).
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A possible workaround, is for you not to use the API and instead the framework internal mechanism: GridManager.GetGridById(gridID).features.cellStyle.addClass(binding, rowIndex, className, false);
I haven't properly tested this workaround, neither, am I sure that it will solve your problem, but I'm hoping, that it can help you to unlock it.
If you find a good solution, feel free to make a PR to the github repo!
cheers,
GR