Process Analysis box zoom

I have an PA chart containing two pens in a pane.
When I use the box zoom, ONLY the active pen Y-axis is adjusted.
before box zoom:

after box zoom:


now the data from the first pen is visualized wrong.

I have made an autoscale cicode which corrects this (after pushing the magnification button top right )

FUNCTION PAAutoScale_bak( STRING sPAName = "", INT nPane = 1)

OBJECT hPen1;
OBJECT hPen2;
OBJECT hAnalyst;
OBJECT hPanes;
OBJECT hPane;
OBJECT hPens;
STRING sPVMax;
STRING sPVMin;
REAL rPVMax;
REAL rPVMin;
REAL rSpanHi;
REAL rSpanLo;

hAnalyst = ObjectByName(sPAName);
hPanes = _ObjectGetProperty(hAnalyst,"Panes");
hPane = _ObjectCallMethod(hPanes,"get_Item",nPane);
hPens = _ObjectGetProperty(hPane,"Pens");

hPen1 = _OBJECTCallMethod(hPens, "get_item", 1);
hPen2 = _OBJECTCallMethod(hPens, "get_item", 2);

sPVMax = _ObjectCallMethod(hPen1, "GetStatistic", "Maximum");
sPVMin = _ObjectCallMethod(hPen1, "GetStatistic", "Minimum");

IF StrToReal(sPVMin) < 400 THEN
	sPVMin = "400";
END

rPVMax = StrToReal(sPVMax);
rPVMin = StrToReal(sPVMin);
	
rSpanHi = rPVMax + (rPVMax-rPVMin)*0.2;
rSpanLo = rPVMin - (rPVMax-rPVMin)*0.2; 

// Message window voor Max - Min waarden
STRING strMessage;
STRING sNewLine = "^n";
STRING ScaleMax = rSpanHi;
STRING ScaleMin = rSpanLo;
strMessage="Max: " + sPVMax + sNewLine + "Min: " + sPVMin + sNewLine + "Scale Max: " + ScaleMax + sNewLine + "Scale Min: " + ScaleMin;
//Message("Info Scales", strMessage,32);


_OBJECTCallMethod(hPen1, "PutVerticalAxisSpan", rSpanLo, rSpanHi);
_OBJECTCallMethod(hPen2, "PutVerticalAxisSpan", rSpanLo, rSpanHi);

END

this corrects the Y-axis scale for both pens like:


Is there a way to trigger the code to be run after the box zoom event?
I do not want to trigger this 'scaling' code every x seconds to correct the Y-axis.

If anyone knows how to do this, much appreciated.