/// <summary>
        /// What happens when we release the mouse button
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CurrentEditor_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            CurrentEditor.ReleaseMouseCapture();
            CurrentStatus = "";
            if (IsDrawing)
            {
                var newAtomPos = e.GetPosition(CurrentEditor);

                //first get the current active visuals
                var landedGroupVisual = CurrentEditor.GetTargetedVisual(newAtomPos) as GroupVisual;
                var landedAtomVisual  = CurrentEditor.GetTargetedVisual(newAtomPos) as AtomVisual;
                var landedBondVisual  = CurrentEditor.GetTargetedVisual(newAtomPos) as BondVisual;

                //check to see whether or not we've clicked and released on the same atom
                bool sameAtom = landedAtomVisual == _currentAtomVisual;

                //check to see whether the target is in the same molecule
                bool sameMolecule = landedAtomVisual?.ParentAtom.Parent == _currentAtomVisual?.ParentAtom.Parent;

                if (landedGroupVisual != null)
                {
                    ClearTemporaries();
                    return;
                }

                //check bonds first - we can't connect to a bond so we need to simply do some stuff with it
                if (landedBondVisual != null)
                {
                    //clicking on a stereo bond should just invert it
                    var parentBond = landedBondVisual.ParentBond;
                    if (parentBond.Stereo == BondStereo.Hatch &
                        EditViewModel.CurrentStereo == BondStereo.Hatch |
                        parentBond.Stereo == BondStereo.Wedge &
                        EditViewModel.CurrentStereo == BondStereo.Wedge)
                    {
                        EditViewModel.SwapBondDirection(parentBond);
                    }
                    else
                    {
                        //modify the bond attribute (order, stereo, whatever's selected really)
                        EditViewModel.SetBondAttributes(parentBond);
                    }
                }
                else //we clicked on empty space or an atom
                {
                    Atom parentAtom = _currentAtomVisual?.ParentAtom;
                    if (landedAtomVisual == null) //no atom hit
                    {
                        if (parentAtom != null)
                        {
                            if (_currentAtomVisual != null)
                            {
                                //so just sprout a chain off it at two-o-clock
                                EditViewModel.AddAtomChain(
                                    parentAtom, _angleSnapper.SnapBond(newAtomPos, e),
                                    ClockDirections.II);
                            }
                            else
                            {
                                //otherwise create a singleton
                                EditViewModel.AddAtomChain(null, newAtomPos, ClockDirections.II);
                            }
                        }
                        else
                        {
                            //create a singleton
                            //otherwise create a singleton
                            EditViewModel.AddAtomChain(null, newAtomPos, ClockDirections.II);
                        }
                    }
                    else //we went mouse-up on an atom
                    {
                        Atom lastAtom = landedAtomVisual.ParentAtom;
                        if (sameAtom) //both are the same atom
                        {
                            if (lastAtom.Element.Symbol != EditViewModel.SelectedElement.Symbol)
                            {
                                EditViewModel.SetElement(EditViewModel.SelectedElement, new List <Atom> {
                                    lastAtom
                                });
                            }
                            else
                            {
                                var atomMetrics = GetNewChainEndPos(landedAtomVisual);
                                EditViewModel.AddAtomChain(lastAtom, atomMetrics.NewPos, atomMetrics.sproutDir);
                                parentAtom.UpdateVisual();
                            }
                        }
                        else //we must have hit a different atom altogether
                        {
                            if (parentAtom != null)
                            {
                                //already has a bond to the target atom
                                var existingBond = parentAtom.BondBetween(lastAtom);
                                if (existingBond != null) //it must be in the same molecule
                                {
                                    EditViewModel.IncreaseBondOrder(existingBond);
                                }
                                else //doesn't have a bond to the target atom
                                {
                                    if (sameMolecule)
                                    {
                                        EditViewModel.AddNewBond(parentAtom, lastAtom, parentAtom.Parent);
                                    }
                                    else
                                    {
                                        EditViewModel.JoinMolecules(parentAtom, lastAtom,
                                                                    EditViewModel.CurrentBondOrder,
                                                                    EditViewModel.CurrentStereo);
                                    }
                                    parentAtom.UpdateVisual();
                                    lastAtom.UpdateVisual();
                                }
                            }
                        }
                    }
                }
            }

            ClearTemporaries();
        }