Thanks very much for the detailed answer! The data is called once the widget is constructed and the update is based on the mouse movement so no need to cast - but I am very happy that this concerns you 
I understand the logic behind adding the children to the grid - you are adding rows, I would need to add columns but that is pretty straight forward. Your approach also tidys up the entire blueprint very nicely!
The probelm with this, though, is that if I have a column with 20 rows, I have to manually plug all 20 rows into the array and manually assign all values to the select. This sounds like manual work that should be done automatically…
May I ask for your opinion on the following?
If I make a child for each and every cell in the entire “spreadsheet”, bind the value to something exposable on spawn and do some math to allocate the proper text, then I would have 3 columns x 5 rows = 15 inherited children in one single master widget. Will the performance drain upscale accordingly?