When editing text in OOo Writer (and possibly, other components) the screen is
not redrawn correctly when a background image is enabled in Page Setup.  I could
reproduce this issue by creating a new text document and setting a background
image (in this case a simple frame from an WMF file (which yields the best PDF
output resolution)) and then entering random text.  As text is rendered it seems
the background image is not rendered again but blockmoved or similar.   This can
be seen most clearly when text is broken across the lines because more text is
entered further up in the same paragraph.  The background image is moved
together with the text when in fact the image should stay in place (and must be
re-rendered because of exposure) and the text should be re-rendered.
Drop me a line and I will provide a testcase if you require one.  However, I
could reproduce the issue easily on my system.  --nts.