When you first start a lesson page there is a control box at the top right of notation are that includes a selection for "popup" and hide and, when appropriate, "autoscroll"  Previously if you selected "popup" the notation would appear in a separate window. A control remained that allowed the selection of restoring the page with the lesson screen and the notation.  Now the notation screen disappears on the lesson screen along with the control box.  The page needs to be reloaded to get the normal split lesson screen / notation.  This is an undesireable change in the interface.