We now realise that we didn't really need 3 rows for vbox1.
Two are sufficient. Select the third row. You may notice that the
Properties window goes blank and from the right mouse button
menu this row of our canvas is nothing more than a
Placeholder. The right mouse button menu Delete will
remove it for us. You could put it back anytime (or indeed place any
row within vbox1) through the right mouse button menu.
Select any widget within vbox1 (e.g., the Words
check button checkbutton1) and then with the right mouse
button traverse the menu to select vbox1-->Insert After.