Hey Tony,
thanks for the help. I was indeed already on the good road towards using the custom buttons, but wanted to have it work in a fully different way. My knowledge about jQuery is too less to understand how I can convert it in my current code.
This is my grid page now (sorry, seems I can not paste code here).
http://www.pressd.be/temp/code.zip
I don't use jQuery directly on my page and I don't want to have the second table show on my page but the “aanpassen offerte” button should just completely open another PHP page in a new tab… Any extra help for me please ?