keep track of floating widget's position in sidebar when undocked
so it will be re-docked in the same position.
Added support for undocking and moving the floating widgets using the
entire titlebar which should be more intuitive.
fixed formatting
Merge pull request #333 from cmv/feature/keep-track-of-floating-widget-sidebar-position

Keep track of floating widget sidebar position. Use full titlebar for docking/moving widgets.