backport SVN commit 921314 by winterz:
backport SVN commit 921314 by winterz:

provide a 20 pixel wide margin on either side of the summary page.
this has 2 benefits:
 1) if you dnd all the summaries from to 1 column, you will still be left  with
    a column on the other side that is wide enough to see as a dnd target if
    decide to dnd a summary back
 2) it looks a little nicer


svn path=/branches/KDE/4.2/kdepim/; revision=923492

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi