There are some hidden interface elements under the left panel. You can see a fragment of a red arrow in the first screenshot. If I resize the left panel I can also see the green tick. I clicked the left panel to detach it, then hovered it back into place to re-attach it but didn't let go of it, and took the second screenshot. Note that you can see the Projection Settings panel even though I didn't click it - I had the Autofit tool selected.