how to detect a click of a grid inside an iframe?

Answer 1

Within the iframe:

The "top" variable (or window.top or self.top) should reference the main frame. You could use something like top.location = nextUri;

Alternatively there is a "target" attribute on links which can specify alternate frames. The link markup would be something like <a href="uri1" target="_top">. You could forward click-events from the row to the link with document.getElementsByTagName("a")[0].click(), assuming that the link is the first one in the row. (The <base> element could also be used.)

Remember that replacing the main frame will require the iframe to be reloaded.

Answer 2

This isn't an answer to your actual question, but if you used properly sized divs with CSS of "overflow: auto", you could get the same layout without needing to communicate across frames.