Layout manager explained

Layout managers are software components used in widget toolkits which have the ability to lay out graphical control elements by their relative positions without using distance units. It is often more natural to define component layouts in this manner than to define their position in pixels or common distance units, so a number of popular widget toolkits include this ability by default. Widget toolkits that provide this function can generally be classified into two groups:

Examples

XUL

In XUL, like the vbox container to stack components on top of each other.