about window message reflection

[aj3423]

Hi
In win32 some window message are sent to the parent's wnd_proc, such as button's WM_COMMAND. I'm trying to understand how the gui libraries handle this, I mean how the Button::on_click() function is called when user clicks on it.
I googled and found that MFC and WTL uses a technique called message reflection, ama cro and virtual functions.
Do all those libraries use technique like this? Any other way?

Thanks