I guess the TVPaint rule is that there must be at least one open project in TVPaint at all times perhaps because all buttons, shortcut keys and program actions need a project in memory to "focus" on?
You are 100% right Svengali. You got the way the current engine works.
That's why it's not that easy to do in terms of C++ development, and not the top priority in the "TO DO" list.
Even if we agree with many things that require to be improved, we have to select the most important ones, and focus on them.
We also need some time to develop new options.
One step after the other.