VOID_DataValue: Cycle backwards on right click.
VOID_DataValue: Cycle backwards on right click.

--- a/VOID_DataValue.cs
+++ b/VOID_DataValue.cs
@@ -108,6 +108,7 @@
 
 	internal interface IVOID_NumericValue
 	{
+		double ToDouble();
 		string ToString(string format);
 		string ToSIString(int digits, int MinMagnitude, int MaxMagnitude);
 	}
@@ -116,11 +117,20 @@
 	{
 		public VOID_NumValue(string Label, Func<T> ValueFunc, string Units = "") : base(Label, ValueFunc, Units) {}
 
+		public abstract double ToDouble();
 		public abstract string ToString(string Format);
 		public abstract string ToSIString(int digits = 3, int MinMagnitude = 0, int MaxMagnitude = int.MaxValue);
 
 		public abstract string ValueUnitString(string format);
-		public abstract string ValueUnitString(ushort digits);
+		
+		public virtual string ValueUnitString(ushort digits) {
+			return Tools.MuMech_ToSI(this.ToDouble(), digits) + this.Units;
+		}
+
+		public virtual string ValueUnitString(ushort digits, int MinMagnitude, int MaxMagnitude)
+		{
+			return Tools.MuMech_ToSI(this.ToDouble(), digits, MinMagnitude, MaxMagnitude) + this.Units;
+		}
 
 		public virtual void DoGUIHorizontal(string format)
 		{
@@ -136,23 +146,43 @@
 			GUILayout.BeginHorizontal(GUILayout.ExpandWidth(true));
 			GUILayout.Label(this.Label + ":", GUILayout.ExpandWidth(true));
 			GUILayout.FlexibleSpace();
-			GUILayout.Label(this.ValueUnitString(digits), GUILayout.ExpandWidth(false));
 			if (precisionButton)
 			{
-				if (GUILayout.Button ("P"))
+				float magnitude = (float)Math.Log10(Math.Abs(this.ToDouble()));
+				GUILayout.Label(this.ValueUnitString(3, int.MinValue, (int)magnitude - digits), GUILayout.ExpandWidth(false));
+				if (GUILayout.Button(digits.ToString()))
 				{
-					digits = (ushort)((digits + 3) % 15);
+					float magLimit = Math.Max(magnitude, 6f);
+					magLimit = (float)Math.Ceiling(magLimit / 3f) * 3f;
+					if (Event.current.button == 0)
+					{
+						digits = (ushort)((digits + 3) % (int)magLimit);
+					}
+					else if (Event.current.button == 1)
+					{
+						digits = (ushort)((digits - 3) % (int)magLimit);
+					}
 				}
 			}
+			else
+			{
+				GUILayout.Label(this.ValueUnitString(digits), GUILayout.ExpandWidth(false));
+			}
 			GUILayout.EndHorizontal();
 
 			return digits;
 		}
+
 	}
 
 	public class VOID_DoubleValue : VOID_NumValue<double>, IVOID_NumericValue
 	{
 		public VOID_DoubleValue(string Label, Func<double> ValueFunc, string Units) : base(Label, ValueFunc, Units) {}
+
+		public override double ToDouble ()
+		{
+			return this.Value;
+		}
 
 		public override string ToString(string format)
 		{
@@ -168,10 +198,6 @@
 			return this.Value.ToString(format) + this.Units;
 		}
 
-		public override string ValueUnitString(ushort digits) {
-			return Tools.MuMech_ToSI(this.Value, digits) + this.Units;
-		}
-
 		public override string ToSIString(int digits = 3, int MinMagnitude = 0, int MaxMagnitude = int.MaxValue)
 		{
 			return string.Format (
@@ -184,15 +210,16 @@
 	public class VOID_FloatValue : VOID_NumValue<float>, IVOID_NumericValue
 	{
 		public VOID_FloatValue(string Label, Func<float> ValueFunc, string Units) : base(Label, ValueFunc, Units) {}
-		
+
+		public override double ToDouble ()
+		{
+			return (double)this.Value;
+		}
+
 		public override string ValueUnitString(string format) {
 			return this.Value.ToString(format) + this.Units;
 		}
 
-		public override string ValueUnitString(ushort digits) {
-			return Tools.MuMech_ToSI((double)this.Value, digits) + this.Units;
-		}
-
 		public override string ToString(string format)
 		{
 			return string.Format (
@@ -215,15 +242,16 @@
 	public class VOID_IntValue : VOID_NumValue<int>, IVOID_NumericValue
 	{
 		public VOID_IntValue(string Label, Func<int> ValueFunc, string Units) : base(Label, ValueFunc, Units) {}
-		
+
+		public override double ToDouble ()
+		{
+			return (double)this.Value;
+		}
+
 		public override string ValueUnitString(string format) {
 			return this.Value.ToString(format) + this.Units;
 		}
 
-		public override string ValueUnitString(ushort digits) {
-			return Tools.MuMech_ToSI((double)this.Value, digits) + this.Units;
-		}
-
 		public override string ToString(string format)
 		{
 			return string.Format (

--- a/VOID_VesselInfo.cs
+++ b/VOID_VesselInfo.cs
@@ -66,7 +66,9 @@
 			"DeltaV (Current Stage)",
 			delegate()
 			{
-				if (Engineer.VesselSimulator.SimManager.Instance.Stages == null)
+				if (Engineer.VesselSimulator.SimManager.Instance.Stages == null ||
+			    	Engineer.VesselSimulator.SimManager.Instance.Stages.Length <= Staging.lastStage
+			    )
 					return double.NaN;
 				return Engineer.VesselSimulator.SimManager.Instance.Stages[Staging.lastStage].deltaV;
 			},