Using ?. and += together

[TonyValenti]

In WPF, you write code like this a lot:

                if (__PART_ActionButton != null) {
                    __PART_ActionButton.Click -= this.PART_ActionButton_Click;
                }

                __PART_ActionButton = value;

                if (__PART_ActionButton != null) {
                    __PART_ActionButton.Click += this.PART_ActionButton_Click;
                }

It would be really nice if I could just do this:

__PART_ActionButton?.Click -= this.PART_ActionButton_Click;
__PART_ActionButton = value;
__PART_ActionButton?.Click += this.PART_ActionButton_Click;

[HaloFour]

#1106

[YairHalberstadt]

Closing as duplicate of #1106