procedure SelectAll;
Builds a selection spanning every character of the current page. In spread display modes (dmTwoPageContinuous, dmTwoPageContinuousWithCover) and when the right-page index is in range, extends the selection across both visible pages so the user gets the full content of the visible spread — including a CR/LF joiner between the per-page slices when round-tripped through SelectedText.
Degrades to a single-page selection on the last odd page of a spread display, or when the right-page text is empty.
Ctrl+A keystroke when AllowUserTextSelection = True and no form field has focus.
PdfView1.SelectAll;
PdfView1.CopySelectionToClipboard;