Typographical prefered placement of graphics, tables etc. is at the top or 
bottom of a page.
OOo provides some possibilities in this direction, but it does not work 
satisfactory yet. If you place a frame at the bottom of a page and anchor it to 
a charactor or paragraph, the frame is placed to another page, as soon as the 
anchor goes to another page. This is correct. 
But there's the same problem as with footnotes. What if the footnote gets 
lengthy and the footnote-anchor is moved to the next page? The only correct 
solution is to split the footnote. 
Of course a frame or graphic cannot be splitted. But there is another possible 
solution:
If the anchor of an object is forced to the next page because the object itself 
hinders it from remaining on the same page, the object should move to the 
designed position of the next page and the anchor can remain on the same page 
until the page is full. I can't think of another way to prevent ugly gaps at the 
end of a page.
Perhaps there is already a possibility to do exactly that. However, I did not 
succed even after hours of trial.