Down key for navigation complete.
Up key is complete.
OnSearchTextBoxKeyUp and OnLibraryContainerViewPreviewKeyDown removed.
Comment added.
OnListBoxItemMouseEnter postpone for next PR.
nextselectedMemberGroupIndex renamed into nextSelectedMemberGroupIndex
nextselectedCategory renamed into nextSelectedCategory
Removed excess value.
Dead comment removed.
Dead comment removed.
Merge branch 'Sitrus2' into DUI-KeyNavigation(use-IsSelected)
IsFocused xaml styling removed.
sender as ListBox is used once.
Merge pull request #193 from vmoyseenko/DUI-KeyNavigation(use-IsSelected)

DUI: key navigation(use is selected). Part 1