<a href="http://trac.openlayers.org/ticket/2077" title="Standardise CSS styling of all OL Controls">OpenLayers Ticket #2077</a> (link now dead) - OpenLayers Control Positioning & Styling.
The left map accepts default positions for the Scaleline, Scale, and MousePosition, so the various controls from Google and OL mutually interfere.
The right map repositions OL controls programmatically by setting left and top styles on each control's div. But surprisingly, as can be seen by giving them translucent backgrounds, OL fails to set sensible width and height styles for them, so most of the map area lies 'beneath' the controls, and, depending on browser, this breaks the dragging of the map &/or the marker, &/or breaks the action of the layer switcher control.
Further, black text controls are fine for the Map baselayer, while white is barely readable, but when either the Satellite or Hybrid baselayers is chosen, it is white that is visible and black barely readable.
This demo uses OpenLayers API , Google Maps API