Hi Mark

Thank you for pointing out that Composer displays several files at a time. I had overlooked it. This is helpful.

The Z-Order Measure Scrolling you describe seems to be what I have in mind. Of course there would be more than 2 horizontal sections possible, but as many as suit a particular situation. The screen might look like the current Window view, except that sections would be divided by narrow horizontal borders.
With an empty score, the area of focus encompassing one bar would move down a Z pass from near the left top corner of the Window, to near the right bottom corner of the Window, while the score is filled in. Any change in space requirement from editing existing notation would be accommodated from screen area to the left and top of the area of focus, leaving the focus point stationary.

I would like to see a lot more tool buttons and would sacrifice precious window area for it. There would be some distinction between tool palettes and general tool buttons, with the user having the ability to select the tool buttons to be displayed and having a choice of small or large tool buttons.

Best wishes

Herbert