var allSel = app.selection; 
var aSel = app.selection[0]; 
var aText = app.documents[0].textFrames.add(); 
aText.contents = "w: " + aSel.width + " , h: " + aSel.height; 
try { 
	aText.left = aSel.geometricBounds[2]; 
	aText.top = aSel.geometricBounds[1]; 
} catch(e) { 
	aText.left = aSel.controlBounds[2]; 
	aText.top = aSel.controlBounds[1]; 
} 

var myCropMarkLengthField = measurementEditboxes.add({editValue:(3*2.83465), editUnits:MeasurementUnits.millimeters, smallNudge:0.5}); 

var allSel = app.selection;  
var aSel = app.selection[0];  
var aText = app.documents[0].textFrames.add();  
aText.contents = "w: " + myMM(aSel.width) + " , h: " + myMM(aSel.height);  
try {  
	aText.left = aSel.geometricBounds[2];  
	aText.top = aSel.geometricBounds[1];  
} catch(e) {  
	aText.left = aSel.controlBounds[2];  
	aText.top = aSel.controlBounds[1];  
}  
 
function myMM(x) { 
	var aMM = x * (25.4/72); 
	return (Math.round(aMM * 1000) / 1000); 
} 

main(); 
 
function main() { 
	var allSel = app.selection;   
	var mX = maxX(); 
	var mY = maxY(); 
	var aText = app.documents[0].textFrames.add();   
	aText.contents = "w: " + myMM(mX - minX()) + " , h: " + myMM(mY - minY());   
 
	aText.left = mX;   
	aText.top = mY;   
}   
  
function myMM(x) {  
	var aMM = x * (25.4/72);  
	return (Math.round(aMM * 1000) / 1000);  
}  
 
function minX() { 
	var mX = app.selection[0].geometricBounds[0]; 
	for (var n = 1; n < app.selection.length; n++) { 
		if (app.selection[n].geometricBounds[0] < mX) { 
			mX = app.selection[n].geometricBounds[0]; 
		} 
	} 
	return mX; 
} 
function maxX() { 
	var mX = app.selection[0].geometricBounds[2]; 
	for (var n = 1; n < app.selection.length; n++) { 
		var aX = app.selection[n].geometricBounds[2]; 
		if (aX > mX) { 
			mX = aX; 
		} 
	} 
	return mX; 
} 
function minY() { 
	var mX = app.selection[0].geometricBounds[3]; 
	for (var n = 1; n < app.selection.length; n++) { 
		if (app.selection[n].geometricBounds[3] < mX) { 
			mX = app.selection[n].geometricBounds[3]; 
		} 
	} 
	return mX; 
} 
function maxY() { 
	var mX = app.selection[0].geometricBounds[1]; 
	for (var n = 1; n < app.selection.length; n++) { 
		var aX = app.selection[n].geometricBounds[1] 
		if (aX > mX) { 
			mX = aX; 
		} 
	} 
	return mX; 
}