How to call a function inside chrome/plug-in from html page?

Question

Hi,

I am developing one Firefox plug-in. In that, I am using sidebar and I am having an iFrame element within that with the source content from a HTML page.

Now, I want to call a JavaScript function which is inside the 'chrome' (i.e. inside the plug-in) by an onClick() event on the HTML page, loaded in the sidebar.

Is it possible? Please help me in this.

The main aim is to highlight the context in the main browser window similar to that present in the HTML page loaded in the sidebar.

Thank you.