> ..., so a user can configure F10 to open it if you, app developer, forgot to mark it as main

So, basically what you want you want, as a user, is to bind arbitrary application actions to shortcuts and force click events in spite of what the developer has predicted or tested in their interface. I do not think this is a trivial problem to solve. The application would need to have a way to expose these actions consistently.

> What is he draws a circle instead of using a letter O? What of it?

Well, then you cannot expect the screen reader to work, for example, and you also cannot expect to do anything with this weird "shape". The developer has broken the standards and the user is helpless in this scenario.