Panel 1: As John works on his layout, we see Liz grabbing onto a crossing sign and asking Daddy what it is because she wants to be part of the process. Since no one seems to have taught her "Look but don't touch", John tries imposing that a bit too late in life if you ask me.
Panel 2: When she grabs onto a railway crossing and asks to work it, she's told to put in down or she'll break it.
This makes John a bad man who's bad because he remembers the glass angel Mike wouldn't stop fiddling around with and how much he had to spend to replace it.
Panel 3: She gets a face full of not NOW when she wants to make a car go.
Panel 4: She turns into Lynn when she yells "Just see if I let you play wiff MY toys!!" as she goes off to get Mommy to yell at Daddy for being greedy and selfish.
Summary: This becomes something of a sinister joke when one remembers that Lynn jealously barred her children from her studio owing to their fear that they'd destroy everything and chase the muses away and so on and so forth.