When text is exported from PDF document using the TextFormatProvider (it's also used internally for the Copy operation), it is automatically split to lines using the vertical position of the words on the page, and small tolerance. 

Currently the tolerance is hard-coded to 0.1 pixels, which is not suitable for documents which contains scanned and OCR-ed text, and there the text lines could be slightly inclined. The result is that words on one slightly inclined line are recognized as if they are on separate lines.