< operating system > A common graphical user interface component, consisting of a permanently visible row of button icons that, when clicked with the mouse , cause the program to perform some action such as printing the current document or changing the mode of operation.
The toolbar buttons often invoke functions accessible via menus but they are easier to use since they are permanently visible. A typical use would be in a paint program where the toolbar allows the users to select one of the various painting "tools" - brush, pencil, bucket etc.
Some application programs under some operating systems may allow the user to customise the functions accessible via toolbars; in others, the choice is fixed by the programmer.
(2003-10-24)