LP1880035: Fix rendering of monograph parts

LP1880035: Fix rendering of monograph parts

A BorderContainer is primarily used to allow anchoring views to the top,
bottom, left, or right of the container and usually allows the use of a
splitter to resize child views. Since we don't use any of that and don't
need such a control, it was apparrently just luck that it worked at all.
Using a plain ContentPane instead allows the page to render as expected.

Thanks to Galen Charlton for tracking this down and finding the fix.

Signed-off-by: Jason Boyer <JBoyer@eoli.info>
Signed-off-by: Jason Stephenson <jason@sigio.com>
Signed-off-by: Bill Erickson <berickxx@gmail.com>