I'm working on a project which is using a lot of datagrids. Disregarding styling the datagrid is a masterpiece in usage.

But styling is a hell. First I wanted to give the header a new style. On the left and right side of the datagrid it should have curved corners. The header has, thanks to the briljant 9-slice-scaling, but why is there a background underneath?

Hmm there seems to be some strange lines between headers, overriding the movieclip (DataHeaderSeperator) with a new one in the library was no success. After a google and a search in the AS of the datagrid I came out with an Actionscript solution:

Flash Actionscript 2.0:
mx.controls.DataGrid.prototype._initHeaders = mx.controls.DataGrid.prototype.initHeaders
mx.controls.DataGrid.prototype.initHeaders = function(Void):Void{
  this._initHeaders();
  for (var i=0; i<this.columns.length; i++) {
    this.header_mc["hO"+i]._visible = false
    this.header_mc["sep"+i]._visible = false
  }
}
mx.controls.DataGrid.prototype.drawHeaderBG = function(Void):Void{
  var mc : MovieClip = this.header_mc;
  mc.clear();
}

Not a very gracefull solution but it works. I'm still searching for a solution to make the background fully transparent.