OverviewMapControl config

In the map I created in openlayers, OverviewMapControl is basically useless from zoom levels 0-3 - the red "extent" rectangle just fills the entire OverviewMapControl and can't actually be used to drag开发者_如何学C the map more then a very minuscule amount. ie. the draggable rectangle would not resize regardless of the zoom level. Can any one help me with this?

Custom Zoom Behavior probably has the information you're looking for; {minRatio: 1, maxRatio: 1} as options to your map constructor might do what you want.