//Interactive Grid / Selection Change / Execute JavaScript       
var i, i_ids = ":"
model = this.data.model;
for ( i = 0; i < this.data.selectedRecords.length; i++ ) 
{
   i_ids += model.getValue( this.data.selectedRecords[i], "Colums_ID") + ":" ;
}
apex.item( "P6_IDS" ).setValue (i_ids);