Changed toggle and always/multi show tabs toolbar to set attribute on
#main-window.
Fixed always show tabs toolbar preference not re-evaluating until after
a tab is opened/closed.
Changed show identity box preference default to false.
Windows - hide titlebar when no separated titlebar, applied, not toggled
and not always showing tabs toolbar.
Changed stacking order so that the toggler doesn't prevent mouse events
on the top pixel of the navigator-toolbox.