func NewWindow(width, height int, title string) *Window {
win := C.glfwCreateWindow(C.int(width), C.int(height), C.CString(title), nil, nil)
if win == nil {
panic("GLFW: Failed to create window.")
}
w := &Window{w: win}
C.glfwSetWindowUserPointer(win, unsafe.Pointer(w))
windows.Lock()
windows.m[win] = w
windows.Unlock()
return w
}
//SetUserPointer sets the user-defined pointer of the window. The current value
//is retained until the window is destroyed. The initial value is nil.
func (w *Window) SetUserPointer(pointer unsafe.Pointer) {
C.glfwSetWindowUserPointer(w.data, pointer)
}