There's a bug in the dashboardlayout component in version
where, when allowDragging: true, panels can be dragged to the top of the page irrespective of other content that may be placed above the dashboardlayout component.
For example if you have an HTML layout structure like this:
With more than three rows of panels, if you place the mouse cursor close to the bottom of any panel in the third row or below and drag it to the top of the page, it will drop hihger than the top of the dashboardlayout screen position thus covering any other content placed at the top of the page above
the dashboardlayout component.
NB Your online demos are still using an older version than
220.127.116.11 where the panel "jumps down" when you are initiating a drag, so this current bug is not reproducible there.