I am working on a module where i have a page that must have no regions or extra content. A kind of "please wait" page.
How do i diable all extra content (regions menus...etc) ? i think Panels has this ability but i can't find the snippet it uses.
On another hand is it possible for a module to specify a special custom page ? like the maintenance-page for example ?
You can create a an extra page.tpl.php specifically for the page where you want to hide the regions. The naming principle is similar to the one for nodes.
Let's say you have a page with the url example.com/content/contact. A template named page--content--contact.tpl.php would serve that page and any page that starts with that url, i.e. the page example.com/content/contact/staff would also use that template (I think).
Check the classes of the body element for clues to what you can name your template, most themes will print that. In my example above, the body element would include the class page-content-contact.