I believe that UI controls should only respond when they receive a mouse down 
event. The zoom control of OOo320m18 Build 9502 (OpenOffice.Ord 3.2.1) responds 
to a mouse up event when the mouse pointer drifts over the control after a 
mouse down event has happened over the horizontal scroll bar. This continually 
causes havic on a very large spreadsheet on a large monitor with a tiny mouse 
pointer. Carefully following a row as one scrolls for dozens of columns only to 
have the sheet explode or disappear causes great confusion ... and it happens 
several times per hour of use. Although the idea behind the scroll widget is 
really great, I would gladly disable it if I could until it is fixed.

TO REPRODUCE:
This will work best on a wide-screen monitor of at least 22" with the 
spreadsheet set to full-screen.
1. Create a spreadsheet with at least 500 columns (the number of rows is 
unimportant)
2. Starting with the scroll thumb under column 1, drag the thumb all the way to 
the right - do not release the mouse button.
3. Move the mouse pointer down until it is hovering over the zoom control.
4. Release the mouse button.
--> If the pointer was over the zoom control to the left or to the right of the 
current position of the zoom slider, the spreadsheet will change the zoom 
factor accordingly and instantly.