AppleScript and non-scriptable applications - applescript

Question

I'm wondering how can I script applications which has no dictionary. All information that I've found tells me nothing. But my experience says me that there is a way.
For example:
tell application "Firefox"
return count of windows
end tell
Will work. And it will work with "Opera" and other applications without dictionary at all. So the questions are:
1) Why does it work?
2) What else work in such a manner? Is there a list of all such actions?
Thank in advance!

Answer 1

You can to some extent script applications without an applescript dictionary by using 'tell application "System Events"'
tell application "Keynote" activate
tell application "System Events" to keystroke "c" using {command down}
end tell
end tell
This example activates Keynote and then copies the current selection. You can use similar code in many applications even if they don't have an applescript dictionary provided you also have the "Enable access for assistive devices" option checked in the "Universal Access" System Preference.
Edit:
This document gives some details of how Cocoa provides some support for Applscript in all applications:
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ScriptableCocoaApplications/SApps_about_apps/SAppsAboutApps.html
Under the heading Built-in Support for Standard and Text Suites

Answer 2

You can open the scripting dictionary of FireFox. Just open AppleScript Editor and go File → show dictionary, and choose FireFox from the list.
It just shows a very rudimentary dictionary. What happens is that the system library provides at least a basic set of commands (called the Standard Suite) to any Carbon or Cocoa app. This is what contains the definitions of window you used.
As Ian already wrote, in order to do more with such an app, you use the so-called UI scripting via System Events.
This nice website is a good place to start.