François's issue was different than the one you are encountering. You can test how in the demo
if ShowFormattingSymbols is enabled, select all does not select the last paragraph-end symbol. This behavior is by design, but it does not affect copying or changing the formatting of the whole document.
In your case, the problem is that the document is not measured and arranged before you try to select and copy it. Please refer to this forum thread
for the answer to your question. You need the following code in particular:
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