I have seen this used on many sites but I do not know what the html code is called. All I know is what it does.

Its the ability to click on the lower right corner of a box and drag it to make it larger.

I would call it an expand window code, but I am not sure.

I need to make a smaller gadget on my blogger page, larger for those who wish to have it larger.

How can I do this with html coding?