Q:

mouse pointer and thumb nail for selection

What would be the appropriate way for selecting a particular row in a paginated view.
For example, while trying to select a particular row in Yahoo Inbox you can use the pointer to select the check box and if you try to click beyond the check box, no action is taken.
But while trying to select a particular row in GMail Inbox you can use the pointer to select it or if you navigate away from the checkbox it changes into a thumbnail but allows you to select the row.
Which method is preferable from a usability perspective and how to implement the thumbnail based selection as done by GMail

A:

Both methods are appropriate, and both can be very usable.
I think the main difference is that row selection (the system used by Gmail) is more like a desktop application and a little less web-like. With links (like in the Yahoo inbox or StackOverflow), it's completely obvious that you're supposed to click on them. With rows, you sort of have to figure that out that you can click them, but I doubt it takes people long.
One thing to keep in mind is that, if you go with row selection, it's probably a good idea to bunch together any other clickable control (like checkboxes, links, or "favorite" stars). This way, you can click anywhere on the row. If you intersperse controls along the row, you increase the likelihood users will make clicking errors (aiming for the row but accidentally clicking some other control), and it will make it harder for users to recognize that the row itself is a clickable region.
So, both are perfectly acceptable user interfaces. You'll have to decide which one is a better match for your particular situation. I think, in general, links are a little bit more versatile, but with clickable rows, you know you can click anywhere and it will work.

