David Edmundson authored Sep 07, 2020 and Vlad Zahorodnii committed Sep 08, 2020

QPointer is a really useful way to store a pointer over time.
It doesn't make have any value as a return value used by a short-lived
method.

There isn't a good copy constructor, it's effectively the same as
creating a new QWeakPointer reference that has to be cleaned up.

Testing if something is null is still the same. A new QPointer can be
made by the caller if it actually is needed.

Input handling is a very hot path called many times a frame, so it's
important to keep this light. focus() and at() are called a lot which
added up to slightly over 1% of CPU time when moving the mouse about.