Issue 54795

there are are lot of screen garbling artifacts in oo.org that people often 
complain about. even though they do not (usually) affect workflow a lot or cause 
serious trouble, they can be annoying and can make a bad impression, especially
if that is a new user or, for example, demonstration of oo.org capabilities :)
so i think we should try to eliminate these cases if that does not require too 
much of an effort.

see testcase.

a) select cell c10. move upper object slightly right or left (not changing its 
heigth).
cell selection that was below object selection handles is not removed (handles.
png)

b) select any cell. move second object on this selection so that selected cell 
is half covered by objects left border
(object-before.png)

select any other cell - suddenly selection below the object is visible and is 
not removed when other cells are selected
(object-after.png)

c) very similar to b, only this time outer border is preserved. select any cell, 
move object as in object-out-before.png

select the cell directly below current selection. now select any other cell. 
cell selection that was not covered by object now is visible
(object-out-after.png)

d) inconsistent cell selection below objects depending on previous object 
placement.
select any cell. drag the object so that it partially covers the cell (callout 
leader line and it's surrounding area counts, too).
now drag it so that filled area covers selection. selection is visible. now drag 
the object away so that no part of it covers selected cell, not even surrounding 
areas of leader line. then drag it back on the selection so that filled object 
area covers selection - selection is not visible through the object.