ViewModify
Unshrink
The Unshrink command restores the normal display of the previously shrunk Viewport.
After starting the command, click on the Viewport to be unshrunk. The command will immediately be applied. The Unshrink command can be used when another command is active without interrupting it.
Using the Unshrink command is equivalent to resetting the Enable flag in the group of the Shrink view category of the Document Properties.