What is the first button...

[sdmaino]

...to the left of the button balloon ???

In other words, what is the function for the up/down arrow  

I tried to tap on it; the image changes from up to down [arrow] and vice-versa, but I cannot see any other difference..

Thanks for any help.

[Itanium]

This button controls the visibility of weather/clock/RSS areas.

If the button is up arrow, only one from these three is visible at a time. Effectively, you switch the same screen space between above mentioned three areas.

Otherwise, if the button is down arrow, you can turn on/off all three individually.

[sdmaino]

Thanks !!!!!