Requests the contents of the clipboard as rich text. When the rich
text is later received, callback will be called.
The text parameter to callback will contain the resulting rich
text if the request succeeded, or NULL if it failed. The length
parameter will contain text's length. This function can fail for
various reasons, in particular if the clipboard was empty or if the
contents of the clipboard could not be converted into rich text form.
Since 2.10
Requests the contents of the clipboard as rich text. When the rich text is later received, callback will be called. The text parameter to callback will contain the resulting rich text if the request succeeded, or NULL if it failed. The length parameter will contain text's length. This function can fail for various reasons, in particular if the clipboard was empty or if the contents of the clipboard could not be converted into rich text form. Since 2.10