I didn't the connection between lambda, inheriting and virtual methods.
Lambdas are basically function objects (closures?) they are not necessarily related to inheritance and virtual functions. How do we compare these? (unless you have a specific code in mind, where somehow these are connected and can be replaced by one-another)
In this case if the function is going to be useful outside the button class, say button class derives from window class and textbox also derived from window class then it makes more sense for it to be virtual function of window class.
Else if its useful elsewhere, as say generic event handler, then it doesn't hurt to be a named lambda/inline function.