Window-owning -controls and non-window-owning controls

Controls are similar to windows in the Window Server in that they are both -bounded areas of the screen and both user interface elements. They are not -synonymous, however, as a control may take up the whole of a window’s area -or only part of it. For this reason controls are divided into two types: window-owning -controls and non-window-owning controls.

Window-owning controls

A window-owning control -has the same size and position as a window in the Window Server. Window-owning -controls may overlap each other and may be moved around the screen within -the bounds of their parent window. Dialogs, menus, toolbars and top-level -controls are typically window-owning controls.

Non-window-owning controls (lodger controls)

The -majority of controls are non-window-owning. A non-window-owning control’s extent typically -covers only part of a window on the screen: usually it is one of a number -of controls within a larger compound control which acts -as a container.

Examples of non-window-owning controls include command -buttons, text boxes and labels.

Non-window-owning controls give greater -efficiency as they require fewer resources in the Window Server and fewer -process switches. They can also result in faster intialisation and redrawing -because a compound control and all its non-window-owning components can be -drawn with a single flush to the window server.

Associated windows

All controls have an associated -window, whether they are window-owning or not. For a window-owning -control the associated window is the window it owns. For a non-window-owning -control the associated window is the window owned by the nearest window-owning -control above it in the control hierarchy.