I understood your issue as you reported it.. and unfortunately for you there is no answer forthcoming from this module's support thread as the two modules are unrelated..
Your "empirical evidence" ignores the fact that none of the code in Google Checkout is related/common to the TPP code.. I have seen nothing in the TPP code which MIGHT cause the issues you describe with ANY payment or checkout module. I know you are frustrated, and I am sorry you do not have a resolution to your issue. However, I'm afraid it appears that no one can give you an answer at this time.. My suggestion is to go to the Google Check support thread and see if the experts for that module can help you work through the issues..
In the entire history of this module (going all the way back to it's roots as Tabbed Products Pro Lite) no one has ever reported a similar issue at all.. (Which is likely why you didn't get any kind of response in this thread until now..)
And to be thorough, I took the liberty of searching through the Google Checkout support thread as well and again saw no other reports of this or a similar issue..
I did see in the Google Checkout threads LOTS of posts with regards to getting Google Checkout to play nice in general. As Delia has said it (Google Checkout) has been historically one of "the most challenging installation of all of them and is very hard to get working properly"
I hope you get it all worked out. However, despite your belief, Tabbed Products Pro could not cause the issues you are describing as it does not affect or modify any of the files where the issue is occurring..
dkerfoot:
While I mentioned that I had recently upgraded to 1.3.9 in the first post - trying to answer the long list of questions we are prompted to answer for clarity dontcha know - it was actually working fine for two days after the upgrade - GCO and all, before I installed TPP. Then GCO stopped working the moment TPP was installed.
Then, a few weeks later, on a fully upgraded and perfectly working separate install, installing TPP again broke GCO.
While your logic clearly seems impeccable in your own mind, it is unfortunate that you are continuing to ignore empirical evidence - i.e.: every time I install the mod it breaks GCO.
You seem unable to conceive of the idea that GCO was working up to and until TPP was installed. Do you get that? GCO was working. Then TPP broke it. TPP broke GCO. GCO was working, then TPP broke it. Got it?
Twice. Same results. GCO worked - TPP broke it. Twice. Are you with me now?
And yes, I can play with colors and font sizes too, aren't you impressed?