ScreenToGif.Modern.con_Transitions_Click C# (CSharp) Method

        private void con_Transitions_Click(object sender, EventArgs e)
        {
            #region Gets the Next Frame

            int indexLast = trackBar.Value == trackBar.Maximum ?
                0 : (trackBar.Value + 1);

            string last = _listFramesEdit[indexLast];

            #endregion

            var transitions = new Transitions(_listFramesEdit[trackBar.Value].From(), last.From(), trackBar.Value, indexLast);

            if (transitions.ShowDialog() == DialogResult.OK)
            {
                #region If Ok

                ResetUndoProp();

                var listToAdd = new List<string>();
                int transitionCount = 0;

                foreach (Bitmap bitmap in transitions.ListToExport)
                {
                    string fileName = _listFramesEdit[trackBar.Value].
                        Replace(".bmp", String.Format("TR{0}.bmp", transitionCount));
                    bitmap.Save(fileName);
                    transitionCount++;

                    listToAdd.Add(fileName);
                }

                _listFramesEdit.InsertRange(trackBar.Value + 1, listToAdd);
                _listDelayEdit.InsertRange(trackBar.Value + 1, transitions.ListDelayExport);

                tvFrames.Add(transitions.ListToExport.Count);
                trackBar.Maximum += transitions.ListToExport.Count;

                #endregion
            }
        }