The buttons at the top of the main window, just below the menu bar, don’t look like buttons that can be clicked. As styled, they look like headings for a list of items that isn’t shown. It took me several days to realize they are clickable to navigate to different parts of the program.
Would it be possible to style these more like normal clickable items? For example style them as buttons, give them icons to look like a toolbar, or color and underline to look like hyperlinks.
I also don’t see any way to activate the functions of them by keyboard navigation. If it’s supposed to be a toolbar control, I’d suggest to add all the functions to the regular menu as well.