about making a drag and drop window with MEL Script

global proc dropCallBackExample( string $dragControl, string $dropControl, string $msg[], int $x, int $y, int $type)
{	
	print "\ndropCallBackExample\n";
	print $dragControl; print "\n";
	print $dropControl;print "\n";
	print $msg[0];print "\n";
	print $x;print "\n";
	print $y;print "\n";
	print $type;print "\n";
}

// This proc MUST return something for drag/dropCallback to work
global proc string[] dragCallBackExample(string $dragControl, int $x, int $y, int $mods)
{
	print "\ndragCallBackExample\n";
	print $dragControl; print "\n";
	print $x;print "\n";
	print $y;print "\n";
	print $mods;print "\n";
	return{"need to return something here"};
}

global proc dropCallBackExampleWin()
{
	window;
		gridLayout -numberOfColumns 2 -cellWidthHeight 50 50;
			button
				-dragCallback dragCallBackExample
				-dropCallback dropCallBackExample
			button1;
			button
				-dragCallback dragCallBackExample
				-dropCallback dropCallBackExample
				button2;
	showWindow;
}
}