Tk_ClipboardAppend(interp, tkwin, target, format, buffer)
These two procedures manage the clipboard for Tk. The clipboard is typically managed by calling Tk_ClipboardClear once, then calling Tk_ClipboardAppend to add data for any number of targets.
Tk_ClipboardClear claims the CLIPBOARD selection and frees any data items previously stored on the clipboard in this application. It normally returns TCL_OK, but if an error occurs it returns TCL_ERROR and leaves an error message in interp->result. Tk_ClipboardClear must be called before a sequence of Tk_ClipboardAppend calls can be issued.
Tk_ClipboardAppend appends a buffer of data to the clipboard. The first buffer for a given target determines the format for that target. Any successive appends for that target must have the same format or an error will be returned. Tk_ClipboardAppend returns TCL_OK if the buffer is successfully copied onto the clipboard. If the clipboard is not currently owned by the application, either because Tk_ClipboardClear has not been called or because ownership of the clipboard has changed since the last call to Tk_ClipboardClear, Tk_ClipboardAppend returns TCL_ERROR and leaves an error message in interp->result.
In order to guarantee atomicity, no event handling should occur between Tk_ClipboardClear and the following Tk_ClipboardAppend calls (otherwise someone could retrieve a partially completed clipboard or claim ownership away from this application).
Tk_ClipboardClear may invoke callbacks, including arbitrary Tcl scripts, as a result of losing the CLIPBOARD selection, so any calling function should take care to be reentrant at the point Tk_ClipboardClear is invoked.