Object level (non-pixel dependent) automation for

Question

I'm looking for some advice and insight on how people approach creating Object-level GUI automation. Technically the type of functionality I am trying to achieve is easily described by Squish software. I want to be able to simulate Key-Press and Mouse Click events without relying on Platform-specific pixel displays, and screen sizes. I've tried to use tools like Sikuli, but unfortunately my application varies too from platform to platform to make reliably re-repeatable tests.

Basically what I am looking for is some advice as to where to look at how 3rd Part (EXTERNAL) programs hook into properties of QT Widgets and other objects. I know a long time ago there was something call QtObjectInspector, but this software required you making Source-Level changes to your Qt code to be compatible on top of being unavailable.

If companies like Squish can do it, how are they doing it? Where do you start? I doubt they are looking at very low level memory interactions, sniffing for "Traffic" that looks like QT on each different system, but I may be wrong.

I'm sorry for such a vague question, but I've been researching for over a day and all I can find now is articles about how amazing Squish is.

Thanks!

EDIT: I looked into QtTestLib, however this doesn't have the "From the outside" kind of access that I am looking for.