actionscript 3 - Invisible height in Flash's CheckBox when used in a ScrollPane for auto-calculation of height -

when using fl.controls.checkbox inside fl.controls.scrollpane, seems whenever last item in scrollpane's children container checkbox, scrollpane's update() method leaves significant blank space below checkbox, although set size of checkbox.

question: how remove invisible height checkbox?

i've researched in many places , found useful post awesome person in link below. credits goes him, infineon. can't trace flash support forum referring though.

http://www.actionscript.org/forums/showpost.php3?p=842806&postcount=6

the solution above invisible height problem hard find dig of flash as3 documentation doesn't turn override protected function configui():void method easily. @ least haven't found till now, , never have known either without kind of prior knowledge inner workings.

*note:* solution doesn't work on checkbox. other form ui widgets fl.controls.radiobutton works same way.

as noted below, because of package hard-coding width , height of rectangle in super class of widget. need override invisible rectangle becomes smaller or editable.

i reproduce code verbatim here prevent link rot:

package com.your.package.here {     import fl.controls.checkbox;     import flash.display.displayobject;     import flash.display.graphics;     import flash.display.shape;     import flash.text.textfieldautosize;      public class widgetcheckbox extends checkbox     {          public function widgetcheckbox()         {         }          override protected function configui():void          {             super.configui();              // remove background movie clip added in superclass             removechild(background);              // redraw hit area of checkbox component             var bg:shape = new shape();             var g:graphics = bg.graphics;             g.beginfill(0, 0);              // draw background area using width , height of              // component, instead of hardcoding these properties ( in             // superclass width , height of rectangle 100 , 100             g.drawrect(0, 0, _width, _height);              g.endfill();             background = bg displayobject;              // add new background             addchildat(background, 0);         }          override public function set label(value:string):void          {             super.label = value;              // in superclass size of label textfield set             // 100 100 px; instead of using these values, autosize             // textfield every time new label set             textfield.multiline = false;             textfield.autosize = textfieldautosize.left;         }     }  } 

then need import new class have extended:

var checkbox:widgetcheckbox = new widgetcheckbox(); 

hope helps people relieve head-scratching.