I am creating a chrome extension - a browser action, but i can also change it to page action if its going to help.

the thing is my client wants to show the user explaination about the extension with any page load. since the icon cant have a lot of text on it.

I couldnt find a solution.. I am looking to have a popup opens near the button with the page load - but it seems impossible - its looks like the popup can show only after clicking.
I thought to inject an iframe on top of the page - but it messes up pages in some cases.

any idea for a solution?