If you have drawn very small objects (or created them via properties), you may find that you can no longer properly select, move, or resize them with the mouse. In this case, there is a remedy!

Go to the display menu – that's the one with the eye – and select the function "Move handles". With sufficiently large objects, nothing happens to the handle points. However, if the object is resized to be too small, the handle points detach, and the object can be further edited.