I searched and tried many different approaches, all failed. There seems to be some javacripts (or something) interacting here (I'm no expert).

So I've decided to try it out by HttpRequests. I was able to submit the form with a quantity of 2 and landed on the next page. I could say "mission accomplished" for now.

I'll keep the thread alive for a little while as a method via the webbrowser could still be interesting for me, in case I fail using httprequests until the end of the app lifecycle.

My concern here is that I may want to take the cookies I got from HttpRequest'ing and "inject" it (somehow) in the webbrowser on the same form. It would be easier for me to continue other steps/pages afterward. I have no idea if this can done tho, and will prolly be asked in another thread.

Thanks for reading.