Size of area or control is invalid

What causes this issue?

The basic form of an area or a control is a rectangle, whose size is
measured in lines (height) and columns (width).
You can change the size of an area or control
on the attribute screen, by changing the length and height values
in the layout editor by setting the bottom right hand corner of the
area to the cursor position.
One of the following has occurred:
The rectangle is smaller than the minimum size required for the
control.
Screen elements within the control no longer fit into the rectangle.
For example, this can happen with subscreens in a tab control.

How to fix this error?

Enlarge the rectangle or move the bottom right hand corner so that none
of the elements within the control is truncated.
There must be at least one blank space between the area and any
elements outside to the left or right.

Error message extract from SAP system. Copyright SAP SE.