What we are trying to do here is play the animation of the buttons in the upper column first, followed by the buttons in the lower column. Since both of the animation groups are parallel animation groups, the buttons belonging to the respective groups will be animated at the same time when the start() function is called.

This time, however, the group is a sequential animation group, which means only a single parallel animation group will be played at a time, followed by the other when the first one is finished. Animation groups are a very handy system that allows us to create very complex GUI animations with simple coding. Qt will handle the difficult part for us so that we don't have to.