Common Desktop Environment: Style Guide and Certification Checklist

Mouse Button Usage

In the Common Desktop Environment, the user can modify mouse mappings to accommodate different working styles. BSelect has been modified to support drag and drop in addition to BTransfer, which has been used historically for Transfer operations in Motif.

Users can set up their systems to use Bselect or BTransfer to perform drag and drops, or use BSelect only. Consider this when you design your application. Check how the user has set the mouse button mappings and use those mappings.



Your application supports the use of mouse button 1 to perform drag-and-drop operations. 

In Motif 1.2, drag and drop is typically performed using button 2 on a three-button mouse (BTransfer). However, in the Common Desktop Environment environment, mouse button 1 (BSelect) should be supported for drag and drop to support mouse usage compatible with other graphical user interface (GUI) environments. A drag can be initiated with either mouse button 1 or mouse button 2. 



When button 2 of a three-button mouse is configured to operate as BAdjust, your application does not perform any BTransfer operations when clicking mouse button 2. 

On a three-button mouse, button 2 is typically used for the BTransfer function. However, in a CDE environment, the user may change an environment setting indicating that mouse button 2 should be used for the BAdjust function instead. BAdjust can be used to extend the selection set in the same manner as Shift+BSelect. 



BSelect should always initiate a drag if the drag is started on a selected item. The drag starts once the drag threshold has been reached. This is true for text regions, scrolling lists, and other similar elements.