Idea Summary
An option to change the spinner style and add a text.

Use Case
There is one spinner only right now, but there are so many alternatives. One overview:

https://cssloaders.github.io/

Maybe more importantly: add a text to the spinner. E.g. “Wait for the process to complete.”, "Do not close or reload this page before the process is completed".

Preferred Solution (Optional)
Additional options in APEX Builder when Show Processing is enabled (spinner custom class, spinner gif, spinner text).

Additional options in apex.util.showSpinner.
Note: this function already has an alert property, but this is “Alert text visually hidden”.