BrightIdeasSoftware.ObjectListView.HandleGroupInfo C# (CSharp) Method

        protected virtual bool HandleGroupInfo(ref Message m)
        {
            NativeMethods.NMLVGROUP nmlvgroup = (NativeMethods.NMLVGROUP)m.GetLParam(typeof(NativeMethods.NMLVGROUP));

            //System.Diagnostics.Debug.WriteLine(String.Format("group: {0}, old state: {1}, new state: {2}",
            //    nmlvgroup.iGroupId, OLVGroup.StateToString(nmlvgroup.uOldState), OLVGroup.StateToString(nmlvgroup.uNewState)));

            // Ignore state changes that aren't related to selection, focus or collapsedness
            const uint INTERESTING_STATES = (uint) (GroupState.LVGS_COLLAPSED | GroupState.LVGS_FOCUSED | GroupState.LVGS_SELECTED);
            if ((nmlvgroup.uOldState & INTERESTING_STATES) == (nmlvgroup.uNewState & INTERESTING_STATES))
                return false;

            foreach (OLVGroup group in this.OLVGroups) {
                if (group.GroupId == nmlvgroup.iGroupId) {
                    GroupStateChangedEventArgs args = new GroupStateChangedEventArgs(group, (GroupState)nmlvgroup.uOldState, (GroupState)nmlvgroup.uNewState);
                    this.OnGroupStateChanged(args);
                    break;
                }
            }

            return false;
        }