How to use base class & child class as parameter in one function ?

[Vinod K Chandran]

On Friday, 22 May 2020 at 12:21:25 UTC, rikki cattermole wrote:
> if (Child child = cast(Child)parent) {
> 	assert(child !is null);
> }

Actually, problem occurs in addHandler function. It expects an 
argument of type "EventArgs", not MouseEventArgs.