How to pass and receive values from popup ctool?

Question

I would like to pass in values from a form via 'get' button that would put what I had in my form textbox1 to the popup modal form textbox1 and then have textbox2 that in modal form to return a value to a secondary textbox2 in my original form.

so something like

form                             popup

textfield1 -> via get button -> popup_textfield1

textfield2 <- via submit button <-popup_textfield2

How do I achieve this? I can't seem to find any article on value pass for ctools