problem on creating dropdown menu?

I want to design dropdown menu.This menu contains two item(save,saveContent).When mouse over on Menu then display below like that
____________
Menu |
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Save |
SaveContent |
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When click on "Save" item then the Menu will be changed to One "TextBox"
and "GO Buttoon" on dropdown menu.
____________
Menu |
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________ |
________| GO |
SaveContent |
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first, is it possible?
if possible, plz tell me the code.

First, I see no point why this should not be possible.
Second, you may want to have a look at the functions replaceChild(), appendChild(), removeChild() and the property [element].style.visibility as well as an event handler tutorial.
Third, what would be the learning effect of only posting some code without your participation?