SortableGridList - fix rounding issue that causes less items to be shown in each row (#3274)

Author: M-i-k-e-l

src/components/gridList/useGridLayout.ts

@@ -37,7 +37,7 @@ const useGridLayout = (props: GridListBaseProps) => {
   }, [numColumns, maxItemWidth, itemSpacing, keepItemSize ? _containerWidth : undefined]);
 
   const itemWidth = useMemo(() => {
-    return (_containerWidth - itemSpacing * (numberOfColumns - 1)) / numberOfColumns;
+    return Math.floor((_containerWidth - itemSpacing * (numberOfColumns - 1)) / numberOfColumns);
 
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [numberOfColumns, itemSpacing, keepItemSize ? undefined : _containerWidth]);