Is there a ready event?

I am new in using this module, but till i know when i use the `.run()` it returns a result after the window is terminated. But can we assign any handler to know when the window is ready?

Start by reading the module's `.run()` entry point and trace when it returns relative to window creation. Determine how readiness could be exposed to callers, and consider the issue complete when callers can observe that the window is ready before it terminates.

Written by the indexing model from the issue text.