When performing the following actions, the user gets an unneeded warning that the row is not empty asking to confirm deletion, while in fact the row is empty.

1) Create a screen with 2 rows and 2 columns
2) Place graph elements in in the first column in both rows.
3) Navigate away from the screen configuration.
4) Return to screen configuration.
5) Drag and drop the graph element on the second row, first column to the first row, second column.
6) Try to remove the empty second row by clicking the symbol
7) Get the attached warning ("This screen-row is not empty. Delete it?")
8) Click OK, the row is deleted and everything is fine.

This might also be true for empty columns, I did not test this.