When navigating through cells with different background colors, the "Background-
color drop-down" (the one with the bucket above a colored rectangle) follows 
the color of the current cell. That is, when the focus is on a cell with no 
background, the button has the transparent (white) color in the rectangle. When 
I click on a cell with a green background, the rectangle becomes green. Back to 
a normal cell, the rectangle is white again.

This is not good. The _current_ color is of no use in this button, because the 
cell has already assigned it! If a want to color multiple cells in my document 
with, say, red. Then I have to focus the cursor on the cell, click the button, 
look for the desired color in the drop-down an click it.

It would be better, if the drop-down remembers my last used color. Then I can 
select a cell and assign it the red color. When I then focus another cell, I 
can _just klick the bucket-button_ and it gets red, too! Without choosing the 
color from the drop-down!

This is the behaviour of Microsoft Office, and Ooo should adapt it soon!