// setBottomOfTFtoBottomOfPrintSpace.jsx 
if (app.selection.length == 0)  
	exit(); 
	 
with (app.selection[0]) { 
	if (app.selection[0].constructor.name == "TextFrame") { 
		var myZeroPoint = app.activeDocument.zeroPoint; // Sichern des Nullpunkts 
		app.activeDocument.zeroPoint = [0, 0]; // Nullpunkt nullen 
		var myBottom = app.activeDocument.documentPreferences.pageHeight - parent.marginPreferences.bottom;  
		var myBounds = geometricBounds; 
		geometricBounds = [myBounds[0], myBounds[1], myBottom, myBounds[3]]; 
		app.activeDocument.zeroPoint = myZeroPoint; // wiederherstellen des Nullpunkts 
	} 
}