Application Express :: How To Pass Parameter / Create New Region / Set Display Point

On package application "Customer Tracking", there is good example about Modal Page. Quite simple but it work quite nicely.The step to create this Modal Page:

- Create new region, set display point: After Header and use region template: Modal Region and set the Static ID (eg. ActivityModal)
- Create the page item and put it on the above region (eyample: Name, Company etc.)
- Create a button, set the action to "Redirect to URL" and enter the URL target to: javascript:openModal('ActivityModal');

Now when you click on the button, the modal page will be display.How can I pass a parameter to the modal page, example: I want to pass text 'Johnny' to the Name page item which is on the modal region.