Common Desktop Environment: Style Guide and Certification Checklist

Expanding the Secondary Pane

The secondary pane provides space for additional options or advanced functionality without increasing the difficulty of the core functionality in the primary pane. The secondary pane can be expanded in a vertical or a horizontal direction. To determine the appropriate direction in which to expand, consider the following questions:



The secondary pane should expand in the direction most consistent with users' expectations, the reading pattern of the language in which it will be displayed, and the content of the information displayed. 



If possible, the panes should have the same default width. 



A separator should be used to separate the primary pane from the secondary pane. 

The user needs to have clear visual feedback as to which elements are part of the primary pane and which elements are part of the secondary pane of the expandable window.