--- a/Plot.c	Wed Jan 22 12:29:28 2014 +0100
+++ b/Plot.c	Wed Jan 22 12:29:38 2014 +0100
@@ -1,134 +1,175 @@
-
 #include <ansi_c.h>
 #include <userint.h>
 
 #include "YLCStuff.h"
-#include "FXAnalyse.h"
-
-#include "FXPlot.h"   // Auto generated panel definitions and protypes
-#include "Plot.h"	  // My own .h file, containing prototypes and definitions for the class Plot...
-
-// ******************* Member functions : constructor and destructor **********************
+#include "FXPlot.h"
+#include "Plot.h"
 
-int Plot_InitPanel(Plot_Data * Instance, const char * title, double PlotMin, double PlotMax, int parent, int control) {
-	
+void Plot_InitPanel(Plot_Data *Instance, const char *title, double ymin, double ymax, int parent, int control)
+{
 	if ((Instance->PlotPanel = LoadPanel (0, "FXPlot.uir", PLOTPANEL)) < 0)
-	return -1;
-	SetPanelAttribute(Instance->PlotPanel, ATTR_TITLE, title) ;  
-	SetPanelAttribute (Instance->PlotPanel, ATTR_CALLBACK_DATA, (void *)Instance); // the panel callback therefore knows which data structure it is associated to 
+		return;
+	
+	SetPanelAttribute(Instance->PlotPanel, ATTR_TITLE, title);  
+	SetPanelAttribute(Instance->PlotPanel, ATTR_CALLBACK_DATA, (void *)Instance);
 	Instance->active = TRUE;
 	Instance->parent = parent;
 	Instance->control = control;
-	Instance->IndexPoint = 0 ;
-	Instance->Mean = 0 ;
+	Instance->IndexPoint = 0;
+	Instance->Mean = 0;
 	Instance->Slope = 0;
-	Instance->ADev = 0 ;
-	Instance->Frequencies = calloc(MAXPOINTSNUMBER, sizeof(double)) ;
-	DisplayPanel (Instance->PlotPanel);
-	SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MIN, PlotMin) ;
-	SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MAX, PlotMax) ;
-	SetAxisScalingMode(Instance->PlotPanel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, PlotMin, PlotMax) ;
-	return 0 ;
+	Instance->ADev = 0;
+	Instance->Frequencies = calloc(MAXPOINTSNUMBER, sizeof(double));
+	DisplayPanel(Instance->PlotPanel);
+	
+	SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MIN, ymin);
+	SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MAX, ymax);
+	
+	if ((ymin != 0.0) && (ymax != 0.0)) {
+		/* manual scaling */
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MIN, ymin);
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MAX, ymax);
+		SetAxisScalingMode(Instance->PlotPanel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, ymin, ymax);
+	} else {
+		/* auto scaling */
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_CHECKBOX_AUTOSCALE, TRUE);
+		SetAxisScalingMode(Instance->PlotPanel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_AUTOSCALE, 0, 0);
 	}
+}
 
 
-
-int Plot_ClosePanel(Plot_Data * Instance) {
+void Plot_ClosePanel(Plot_Data * Instance)
+{
 	Instance->active = FALSE;
 	free(Instance->Frequencies);
 	SetCtrlVal(Instance->parent, Instance->control, FALSE);
-	DiscardPanel (Instance->PlotPanel); 
-	return 0;
-	}
-			
-	
+	DiscardPanel(Instance->PlotPanel); 
+}
+
 
-// ******************** Member functions, callbacks (private) *******************************
+void Plot_AddFrequency(Plot_Data * Instance, double Freq)
+{
+	double Drift = 0;
+	int DeDrift;
+	int N = 0;
 
-int CVICALLBACK CB_PlotEvent(int panel, int event, void *callbackData, int eventData1, int eventData2) {
+	double Mean  = Instance->Mean;
+	double Slope = Instance->Slope;
+	double ADev  = Instance->ADev; 
+	
+	/* Correct Freq with drift (feed forward) if dedrift is on */
+	GetCtrlVal(Instance->PlotPanel, PLOTPANEL_CHECKBOX_DEDRIFT, &DeDrift);
+	if (DeDrift) {
+		GetCtrlVal(Instance->PlotPanel, PLOTPANEL_DEDRIFT, &Drift);
+		Freq -= ((double) Instance->IndexPoint)*Drift;
+	}
+	
+	/* Add Freq to graph plot */
+	Instance->Frequencies[Instance->IndexPoint++] = Freq;
+	N = Instance->IndexPoint;
+	
+	if (N > 1) {
+		/* adev and slope computation need at least 2 data points */
+		Instance->Slope = (Slope*(N-2) + 6*(Freq-Mean)/N)/(N+1);
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_SLOPE, Instance->Slope);
+		Instance->ADev = sqrt( ( ADev*ADev*(N-2) + 0.5*pow(Freq-Instance->Frequencies[N-2],2) ) / (N-1));
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_ADEV, Instance->ADev);
+	}
+	Instance->Mean = (Mean*(N-1)+Freq)/N;
+	SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MEAN, Instance->Mean);
 	
-	int VirtualKeyCode;
-	int StepIndex;
-	double Step;
+	/* if too many points recorded restart */
+	if (N > MAXPOINTSNUMBER - 2) {
+		Instance->IndexPoint = 0;
+		Instance->Mean = 0;
+		Instance->Slope = 0;
+		Instance->ADev = 0;
+		SetCtrlVal(Instance->PlotPanel,PLOTPANEL_MEAN, 0.0);
+		SetCtrlVal(Instance->PlotPanel,PLOTPANEL_SLOPE, 0.0);
+		SetCtrlVal(Instance->PlotPanel,PLOTPANEL_ADEV, 0.0);
+	}
+	
+	DeleteGraphPlot(Instance->PlotPanel, PLOTPANEL_FREQPLOT, -1, VAL_IMMEDIATE_DRAW);
+	PlotY(Instance->PlotPanel, PLOTPANEL_FREQPLOT, Instance->Frequencies, Instance->IndexPoint,
+		VAL_DOUBLE, VAL_THIN_LINE, VAL_EMPTY_SQUARE, VAL_SOLID, 1, VAL_BLUE);
 	
-	Plot_Data * Instance = NULL;
-	
+	int autoscale;
+	GetCtrlVal(Instance->PlotPanel, PLOTPANEL_CHECKBOX_AUTOSCALE, &autoscale);
+	if (autoscale) {
+		/* update plot limits */
+		double ymin, ymax;
+		GetAxisScalingMode(Instance->PlotPanel, PLOTPANEL_FREQPLOT,VAL_LEFT_YAXIS, NULL, &ymin, &ymax);
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MIN, ymin);
+		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MAX, ymax);
+		/* adjust control limits */
+		SetCtrlAttribute(Instance->PlotPanel, PLOTPANEL_MIN, ATTR_MAX_VALUE, ymax);
+		SetCtrlAttribute(Instance->PlotPanel, PLOTPANEL_MAX, ATTR_MIN_VALUE, ymin);
+	}
+}
+
+
+/* callbacks */
+
+int CVICALLBACK CB_PlotEvent(int panel, int event,
+		void *callbackData, int eventData1, int eventData2)
+{
 	switch (event)
 	{
-	case EVENT_CLOSE:
-		GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &Instance);  
-		Plot_ClosePanel(Instance) ;
-		break;
+		case EVENT_CLOSE:
+			Plot_Data *data;
+			GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &data);
+			Plot_ClosePanel(data);
+			break;
 	
-	case EVENT_KEYPRESS:
-		VirtualKeyCode = GetKeyPressEventVirtualKey(eventData2);
-		switch (VirtualKeyCode)
-		{
-		case 2304: //ie right arrow
-			GetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, &StepIndex);
-			if (StepIndex<10){
-				SetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, ++StepIndex) ;
-				GetCtrlVal(panel, PLOTPANEL_SCALINGSTEP, &Step);
-				SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_INCR_VALUE, Step) ;
-				SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_INCR_VALUE, Step) ;
-			};
+		case EVENT_KEYPRESS:
+			int keycode = GetKeyPressEventVirtualKey(eventData2);
+			int index;
+			double step;
+			switch (keycode)
+			{
+				case 2304: /* right arrow */
+					GetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, &index);
+					if (index < 10) {
+						SetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, ++index);
+						GetCtrlVal(panel, PLOTPANEL_SCALINGSTEP, &step);
+						SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_INCR_VALUE, step);
+						SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_INCR_VALUE, step);
+					}
+					break;
+				case 2048: /* left arrow */
+					GetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, &index);
+					if (index > 0) {
+						SetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, --index);
+						GetCtrlVal(panel, PLOTPANEL_SCALINGSTEP, &step);
+						SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_INCR_VALUE, step);
+						SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_INCR_VALUE, step);
+					}
+					break;
+			}
 			break;
-		case 2048: //ie left arrow
-			GetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, &StepIndex);
-			if (StepIndex>0){
-				SetCtrlIndex(panel, PLOTPANEL_SCALINGSTEP, --StepIndex) ;
-				GetCtrlVal(panel, PLOTPANEL_SCALINGSTEP, &Step);
-				SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_INCR_VALUE, Step) ;
-				SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_INCR_VALUE, Step) ;
-				};
-			break;
-		};
-		break;
 	}
 	return 0;
 }
 
-int CVICALLBACK Plot_CB_ChangeMax (int panel, int control, int event,
+
+int CVICALLBACK Plot_CB_ChangeYLim (int panel, int control, int event,
 		void *callbackData, int eventData1, int eventData2)
 {
-	double YMin, YMax ;
-
-	switch (event)
-		{
-		case EVENT_COMMIT:
-			GetCtrlVal(panel, PLOTPANEL_MIN, &YMin) ;
-			GetCtrlVal(panel, PLOTPANEL_MAX, &YMax) ;
-			if (YMin<YMax) {
-				SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, YMin, YMax) ;
-				SetCtrlVal(panel, PLOTPANEL_CHECKBOX_AUTOSCALE, FALSE) ; 
-				} ;
-			break;
-		case EVENT_RIGHT_CLICK:
-
-			break;
-		}
-	return 0;
-}
-
-int CVICALLBACK Plot_CB_ChangeMin (int panel, int control, int event,
-		void *callbackData, int eventData1, int eventData2)
-{
-	double YMin, YMax ;
+	double ymin, ymax;
 	
 	switch (event)
-		{
+	{
 		case EVENT_COMMIT:
-				GetCtrlVal(panel, PLOTPANEL_MIN, &YMin) ;
-				GetCtrlVal(panel, PLOTPANEL_MAX, &YMax) ;
-				if (YMin<YMax ) {     
-					SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, YMin, YMax) ;
-					SetCtrlVal(panel, PLOTPANEL_CHECKBOX_AUTOSCALE, FALSE) ;
-					} ;
+			GetCtrlVal(panel, PLOTPANEL_MIN, &ymin);
+			GetCtrlVal(panel, PLOTPANEL_MAX, &ymax);
+			/* adjust control limits */
+			SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_MAX_VALUE, ymax);
+			SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_MIN_VALUE, ymin);
+			/* disable autoscaling */
+			SetCtrlVal(panel, PLOTPANEL_CHECKBOX_AUTOSCALE, FALSE);
+			SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, ymin, ymax);
 			break;
-		case EVENT_RIGHT_CLICK:
-
-			break;
-		}
+	}
 	return 0;
 }
 
@@ -136,126 +177,63 @@
 int CVICALLBACK Plot_CB_ChangeAutoScale (int panel, int control, int event,
 		void *callbackData, int eventData1, int eventData2)
 {
-	bool AutoScale = FALSE;
-	int NotCare  = 20000000 ;
-	double YMin = 10000000 , YMax = 64000000 ;
+	int autoscale = FALSE;
+	double ymin, ymax;
 	
 	switch (event)
-		{
+	{
 		case EVENT_COMMIT:
-			GetCtrlVal(panel, PLOTPANEL_CHECKBOX_AUTOSCALE, &AutoScale) ;
-			if (AutoScale) {
-				SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_AUTOSCALE, YMin, YMax) ;
-				GetAxisScalingMode(panel, PLOTPANEL_FREQPLOT,VAL_LEFT_YAXIS, &NotCare, &YMin, &YMax ) ;
-				SetCtrlVal(panel, PLOTPANEL_MIN, YMin);
-				SetCtrlVal(panel, PLOTPANEL_MAX, YMax);
-				}
-			else {
-				GetCtrlVal(panel, PLOTPANEL_MIN, &YMin);
-				GetCtrlVal(panel, PLOTPANEL_MAX, &YMax);
-				SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, YMin, YMax) ;
-				} ;
+			GetCtrlVal(panel, PLOTPANEL_CHECKBOX_AUTOSCALE, &autoscale);
+			if (autoscale) {
+				SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_AUTOSCALE, 0, 0);
+				GetAxisScalingMode(panel, PLOTPANEL_FREQPLOT,VAL_LEFT_YAXIS, NULL, &ymin, &ymax);
+				SetCtrlVal(panel, PLOTPANEL_MIN, ymin);
+				SetCtrlVal(panel, PLOTPANEL_MAX, ymax);
+				/* adjust control limits */
+				SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_MAX_VALUE, ymax);
+				SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_MIN_VALUE, ymin);
+			} else {
+				GetCtrlVal(panel, PLOTPANEL_MIN, &ymin);
+				GetCtrlVal(panel, PLOTPANEL_MAX, &ymax);
+				SetAxisScalingMode(panel, PLOTPANEL_FREQPLOT, VAL_LEFT_YAXIS, VAL_MANUAL, ymin, ymax);
+			}
 			break;
-		case EVENT_RIGHT_CLICK:
-
-			break;
-		}
+	}
 	return 0;
 } 
 
+
 int  CVICALLBACK Plot_CB_ChangeScalingStep(int panel, int control, int event,
 		void *callbackData, int eventData1, int eventData2)
 {
-	double ScalingStep ;
+	double step;
 
 	switch (event)
-		{
+	{
 		case EVENT_COMMIT:
-			GetCtrlVal(panel, PLOTPANEL_SCALINGSTEP, &ScalingStep) ;
-			SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_INCR_VALUE, ScalingStep) ;
-			SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_INCR_VALUE, ScalingStep) ;
+			GetCtrlVal(panel, PLOTPANEL_SCALINGSTEP, &step);
+			SetCtrlAttribute(panel, PLOTPANEL_MIN, ATTR_INCR_VALUE, step);
+			SetCtrlAttribute(panel, PLOTPANEL_MAX, ATTR_INCR_VALUE, step);
 			break;
-		case EVENT_RIGHT_CLICK:
-			break;
-		}
+	}
 	return 0;
 }
 
 
-// ******************** Member functions, public *******************************************
-
-int Plot_AddFrequency(Plot_Data * Instance, double Freq) {
-
-	double YMin = 10000000, YMax = 64000000, Mean = 0, ADev = 0 , Slope = 0 , Drift = 0 ;
-	bool AutoScale, DeDrift ;
-	int N = 0, NotCare ;
-
-	// Retrieve previous values for mean, adev and slope
-	Mean  = Instance->Mean ;
-	Slope = Instance->Slope;
-	ADev  = Instance->ADev; 
-	
-	// Correct Freq with drift (feed forward) if dedrift is on
-	GetCtrlVal(Instance->PlotPanel, PLOTPANEL_CHECKBOX_DEDRIFT, &DeDrift) ;
-	if(DeDrift) {
-		GetCtrlVal(Instance->PlotPanel, PLOTPANEL_DEDRIFT, &Drift) ;
-		Freq -= ((double) Instance->IndexPoint)*Drift ;
-		} ;
-	
-	// Add Freq to graph plot
-	Instance->Frequencies[Instance->IndexPoint++] = Freq ;
-	N = Instance->IndexPoint ; // N is now the new number of points in the graph
-	
-	
-	if (N > 1) {   // ADEV and SLOPE need at least 2 values !
-		Instance->Slope = (Slope*(N-2) + 6*(Freq-Mean)/N)/(N+1) ;
-		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_SLOPE, Instance->Slope ) ;
-		Instance->ADev = sqrt( ( ADev*ADev*(N-2) + 0.5*pow(Freq-Instance->Frequencies[N-2],2) ) / (N-1) ) ;
-		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_ADEV, Instance->ADev ) ;  	
-		} ;
-	Instance->Mean = (Mean*(N-1)+Freq)/N ; 
-	SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MEAN, Instance->Mean);
-	
-	if (N > MAXPOINTSNUMBER - 2) { // If too many points recorded, restart new plot with new values of Mean, Slope and Adev
-		Instance->IndexPoint = 0;
-		Instance->Mean = 0;
-		Instance->Slope = 0;
-		Instance->ADev = 0;
-		SetCtrlVal(Instance->PlotPanel,PLOTPANEL_MEAN, 0.) ;
-		SetCtrlVal(Instance->PlotPanel,PLOTPANEL_SLOPE, 0.) ;
-		SetCtrlVal(Instance->PlotPanel,PLOTPANEL_ADEV, 0.) ;
-		} ;
-	
-	DeleteGraphPlot(Instance->PlotPanel, PLOTPANEL_FREQPLOT, -1,VAL_IMMEDIATE_DRAW) ;
-	PlotY(Instance->PlotPanel, PLOTPANEL_FREQPLOT, Instance->Frequencies, Instance->IndexPoint, VAL_DOUBLE, VAL_THIN_LINE, VAL_EMPTY_SQUARE, VAL_SOLID, 1, VAL_BLUE) ; 
-	GetCtrlVal(Instance->PlotPanel, PLOTPANEL_CHECKBOX_AUTOSCALE, &AutoScale) ;
-	if (AutoScale) {
-		GetAxisScalingMode(Instance->PlotPanel, PLOTPANEL_FREQPLOT,VAL_LEFT_YAXIS, &NotCare, &YMin, &YMax ) ;
-		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MIN, YMin);
-		SetCtrlVal(Instance->PlotPanel, PLOTPANEL_MAX, YMax);
-		} ;
-	return 0 ;
-	}
-
-
-
-
 int CVICALLBACK Plot_CB_Reset (int panel, int control, int event,
 		void *callbackData, int eventData1, int eventData2)
 {
-	Plot_Data * Instance = NULL;
-	
+	Plot_Data *data;
 	switch (event)
-		{
+	{
 		case EVENT_COMMIT:
-			GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &Instance);
-			Instance->IndexPoint = 0 ;
-			Instance->Mean = 0 ;
-			Instance->Slope = 0;
-			Instance->ADev = 0 ;
-			
+			GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &data);
+			data->IndexPoint = 0;
+			data->Mean = 0;
+			data->Slope = 0;
+			data->ADev = 0;
 			break;
-		}
+	}
 	return 0;
 }
 
@@ -263,63 +241,50 @@
 int CVICALLBACK Plot_CB_GetDrift (int panel, int control, int event,
 		void *callbackData, int eventData1, int eventData2)
 {
-	Plot_Data * Instance = NULL;
-	bool DeDrift ;
-	double Drift ;
+	Plot_Data *data;
+	int dedrift;
+	double drift;
 	
 	switch (event)
-		{
+	{
 		case EVENT_COMMIT:
-			
-			//Instance = ThisPlot(panel) ;
-			GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &Instance);  
-			GetCtrlVal(panel, PLOTPANEL_CHECKBOX_DEDRIFT, &DeDrift) ;
-			
-			if (!DeDrift) {
-				SetCtrlVal(panel,PLOTPANEL_DEDRIFT,Instance->Slope) ;
-				}
-			else {
-				GetCtrlVal(panel, PLOTPANEL_DEDRIFT, &Drift) ;
-				Drift += Instance->Slope ;
-				SetCtrlVal(panel, PLOTPANEL_DEDRIFT, Drift) ;
-				
-				Instance->IndexPoint = 0 ;
-				Instance->Mean = 0 ;
-				Instance->Slope = 0 ;
-				Instance->ADev = 0 ;
-				
-				} ;
-			
-			
+			GetPanelAttribute(panel, ATTR_CALLBACK_DATA, &data);  
+			GetCtrlVal(panel, PLOTPANEL_CHECKBOX_DEDRIFT, &dedrift);
+			if (dedrift) {
+				GetCtrlVal(panel, PLOTPANEL_DEDRIFT, &drift);
+				drift += data->Slope;
+				SetCtrlVal(panel, PLOTPANEL_DEDRIFT, drift);
+				data->IndexPoint = 0;
+				data->Mean = 0;
+				data->Slope = 0;
+				data->ADev = 0;
+			} else
+				SetCtrlVal(panel,PLOTPANEL_DEDRIFT, data->Slope);
 			break;
-		}
+	}
 	return 0;
 }
 
+
 int CVICALLBACK Plot_CB_ChangeDrift (int panel, int control, int event,
 		void *callbackData, int eventData1, int eventData2)
 {
-	bool DeDrift ;
-	Plot_Data * Instance = NULL;
+	int dedrift;
+	Plot_Data *data;
 	
 	switch (event)
-		{
+	{
 		case EVENT_COMMIT:
-			GetCtrlVal(panel, PLOTPANEL_CHECKBOX_DEDRIFT, &DeDrift) ;
-			if(DeDrift) { 
-				
-				//Instance = ThisPlot(panel) ;
-				GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &Instance);  
-			
-				Instance->IndexPoint = 0 ;
-				Instance->Mean = 0 ;
-				Instance->Slope = 0 ;
-				Instance->ADev = 0 ;
-				
-				} ;		
-
+			GetCtrlVal(panel, PLOTPANEL_CHECKBOX_DEDRIFT, &dedrift);
+			if (dedrift) {
+				GetPanelAttribute (panel, ATTR_CALLBACK_DATA, &data);
+				data->IndexPoint = 0;
+				data->Mean = 0;
+				data->Slope = 0;
+				data->ADev = 0;
+			}
 			break;
-		}
+	}
 	return 0;
 }