Adjustment handle

In graphical user interfaces, the control element adjustment handle is a small box that appears on the corners and edges of a selected element such as another graphical control element like a window. This allows the user to alter size or shape.¹

By dragging and dropping the control handle onto an edge, the user can make the control wider or narrower, taller or shorter. Corner handles let one move two edges at once.²

An adjustment handle can also be used in audio editing software.³