In tutorial:“Tutorial: Responsive GUI layouts using FlexBox and Grid”, it define a 1 row and 3 columns grid. How to define a 2 row and 3 columns grid? The first row’s three items are the same as the second row’s three items.
You cannot have the same instance appear twice. So the layout will place the
leftPanel on the top row and later place it in the lower row, and same for the others. You won’t see it in the top row, since the painting only happens after the whole layout run (
resized()) has finished.