Delphi: Change RadioButton.Checked or CheckBox.Checked without triggering OnClick-Event

When changing the state of a RadioButton or a Checkbox by code - for example when setting Checked to True or False - automatically, the OnClick-Event of the option switch will be triggered. Today, I want to show you, how you can prevent the OnClick Event from executing.

OnClick-Event will be executed

RadioButton1.Checked := True;

// or

CheckBox1.Checked := True;

OnClick-Event will be prevented

procedure ChangeState(NewState: boolean);
var
  OldEvent: TNotifyEvent;
begin
  // remember old event
  OldEvent := RadioButton1.OnClick;
  RadioButton1.OnClick := nil;

  // apply changes, for example:
  RadioButton1.Checked := NewState;

  // reset event
  RadioButton1.OnClick := OldEvent;
end;

The trick is: We remember the procedure assigned to the OnClick Event in the variable OldEvent. After that, we set OnClick to nil. With this, there is no procedure assigned anymore and we can apply the changes without any problems. Because, also after the changes, it should work like before, we reset the event in a last step. In the example, we have used a RadioButton, but, of course, this also works with a CheckBox in the same way.