DesktopTextControl.Copy
From Xojo Documentation
Method
Copies the selected text in the TextArea to the Clipboard, including the styled text information.
Example
This example copies the selected text and places it on the Clipboard.
TextArea1.SelectionStart = 0
TextArea1.SelectionLength = 10
TextArea1.Copy
TextArea1.SelectionLength = 10
TextArea1.Copy