Common Widgets provides operations to interact with the platform clipboard, which holds data to be transferred between applications. An application can copy data from Smalltalk to the clipboard, and paste data from the clipboard into Smalltalk.

Data stored in the clipboard has an associated format name, which applications use to identify the type of data. Common Widgets automatically handles two predefined formats, string and pixmap, which are mapped to the corresponding platform-specific format during clipboard operations. Applications can also work with platform-specific formats, or define new proprietary formats. The format names and corresponding buffer object classes used to represent data when working with the clipboard include the following:

The class CgDisplay implements the clipboard operations. All operations require a CgWindow parameter, which identifies the application to the OS window system. The window can be any valid CgWindow. The available clipboard operations include the following: