The Instructor Window (IW) has no effect.
I did this test:
1 - Start SU. SU starts with the Select Tool active. The cursor is an arrow.
2 - Open the IW.
3 - Choose the Line Tool.
4 - Bring the cursor in the drawing area. The cursor is still an arrow.
5 - Click once. The cursor change to the Pen (Line Tool) but no line is started.
6 - Click again to start a line.
I closed SU with the IW still open.
I started it again and do the same test with the same result.
I quit then start again then close the IW and repeat the test. Same results.
What is bugging me is that the cursor doesn’t change when I select a tool. With SU 2019, as soon as I select a tool, the cursor changes immediately to the appropriate icon. Of course, as soon as I bring the cursor in the drawing area, I can start drawing with the first click.
SU 2020 and 2021 broke something, unless there is a plugin that messes things up.