After you select text, you can copy it anywhere within a window if the application supports text editing. You can also copy between such applications or from a terminal emulator window to a window that supports text editing. You can copy text in different waysthe choice depends largely on which window you want active after completing the copy operation. Position the cursor where you want the text copied by pointing and clicking MB1. The text is copied to the new location.
Some applications use different methods for copying text.
See that application's documentation for an explanation of how to copy text in that application. When copying text between windows using the method just described, the window in which you select the text takes input focus. If that window is not the one in which you are currently working, and to which you copied the text, then you have to reestablish focus to continue your work once you finish the copy. QuickCopy is a way to grab a piece of text from another window without changing focus. QuickCopy cannot be used if you use pointer focus.