As you'll have noticed in the preceding example, each widget expects the parent to be passed to the constructing function. This enables the Qt framework to handle the tidying up, and freeing of memory when a tree of widgets is removed. QObject (which is the base object for all of the Qt API) keeps track of its child objects and so, when being removed, can remove its children too. This makes the creation and deletion of complex widget hierarchies easier to handle correctly. To make use of this feature, you should always remember to pass the parent object to a widget's constructor (the Go functions starting with New...), despite the fact that passing nil may look like it's working.