var arr = [new Btn(), new Btn(), new Btn()];
PlaceTools.distribute(arr, 20, PlaceTools.HORIZONTAL);
    /*
    ./Main.hx:13: characters 24-25 : Array<Btn> should be Array<Xywh>
    //Main.hx:13: characters 24-25 : Type parameters are invariant
    ./Main.hx:13: characters 24-25 : Btn should be Xywh
    ./Main.hx:13: characters 24-25 : Btn should be { y : Float, x : Float, width : Float, height : Float }
    ./Main.hx:13: characters 24-25 : For function argument 'arr'
    */

[new Btn(), new Btn(), new Btn()].distribute(20, PlaceTools.HORIZONTAL);
    /*
    ./Main.hx:24: characters 2-46 : Array<Btn> has no field distribute
    */

PlaceTools.distribute([new Btn(), new Btn(), new Btn()], 20, PlaceTools.HORIZONTAL);
    /*
    Compiles and runs.
    */

typedef Xywh = {x:Float, y:Float, width:Float, height:Float};
class Btn extends flash.display.Sprite{public function new() super()}
using Main;

//------------------------------
public static function distribute(arr:Array<Xywh>, ?padding:Int=0, ?dtype:String="horizontal")
{