That's one small step for source code, one giant leap for event handling.

Before this change this code:
```csharp
checkBox.Toggled += picker_ValueChanged;
checkBox.Toggled += picker_ValueChanged1;
checkBox.Toggled += picker_ValueChanged2;
checkBox.Toggled -= picker_ValueChanged;
```
Would result in none of events working. After this change work as it should and 1 and 2 are called. 
Also in Wpf this was not working:
```csharp
checkBox.Toggled += picker_ValueChanged;
checkBox.Toggled -= picker_ValueChanged;
checkBox.Toggled += picker_ValueChanged;
```
It called twice because underlying handler for first was never removed.