void MyFrame::OnMouseEnter(wxMouseEvent& event) { // handle the event here } BEGIN_EVENT_TABLE(MyFrame, wxFrame) EVT_ENTER_WINDOW(MyFrame::OnMouseEnter) END_EVENT_TABLE()In this example, we define a function called `OnMouseEnter` that will be called when the mouse cursor enters the window associated with `MyFrame`. We use the `BEGIN_EVENT_TABLE` macro to associate this function with the `EVT_ENTER_WINDOW` event. This event is part of the wxWidgets library, a cross-platform GUI toolkit written in C++.