friend,
Here is one interesting fact of F4 key...
In MSOFFICE, Use of F4 key will save our time... It will do the same what we did previously before using this F4 key....
Example,when working with word document, we wont concentrate on changing formate while typing... After typing the entire document,we go to the each side heading and we make correspondent change in formate....
Instead of doing change to each side heading separately... just do the formation a single side heading and take our cursor to the next side heading and press F4 key.. It will make a similar change to it...

even, if your deleting a letter form the word "not possible"..After pressing DEL key,it will"ot possible"..then if you press F4 key, it will be "t possible".. again if you press F4 for 2 more times then it will be " possible"...   

In excel, if you are copying a cell content to next 10 cells by clicking and dragging and next if you feeling of copying it to further 10 more cells then just  press F4 key.. it will do the same...

Interesting na?