Q:

Cocoa accessibility API, can I click a window in the background without activating it?

I've been searching forever for a solution to this, so I thought I'd seek out the brainpower of greater minds than mine.  I'm developing a Cocoa app that uses the Accessibility API to manipulate another program (it's a hotkey app).  The app I'm controlling typically has multiple windows open, with some hidden behind others.  What I would like to do, if it's possible, is to send mouse events to windows using the Accessibility API in a way that presses a button in the window without bringing it to the foreground (interact with the window but don't activate it).  The reason I'm trying to do this is that sending the mouse event to this other window will force it to the foreground and disrupt the user's interaction with the foremost window.  
This is possible on Windows - apparently, because apps similar to mine do it there - but I'm getting the feeling that this isn't possible with Cocoa, given the way the window manager works.  Am I mistaken?

A:

Accessibility is higher-level than that. You send, for example, AXPress actions to AXButton objects, but “press” is not necessarily a click—pressing the space bar while a view is focused, for example, is also a “press”. AXPress is a high-level action that means “do your thing”, which obviously has meaning for some views (such as buttons) and not others (such as fields).
Accessibility activating the application does make sense when you look at it from its intended purpose: Assistive devices for disabled users. If the user “presses” something by whatever means, they probably intend to activate the application and work in it.
Quartz Event Services will get you almost there: You can create an event tap for the process you want to control, and you can forge events and send them to a tap. The catch is that you can only send events to a tap when the tap fires—i.e., when the application already has an event to deal with. When it doesn't, you're stuck.

