improvement for bar tag with slider.
-fix bug the slider is drawn outside of the bounds (FS#11658).
-offset the slider position so that the center of the slider indicates current position.
-add nobar option. if this option is set, the bar isn't drawn at all.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28248 a1c6a512-1295-4272-9138-f99709370657
4 files changed