Description:
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pdf_show_boxed() normally wraps lines between words.  If a string containing unbroken characters is fed to pdf_show_boxed() such that the unbroken characters render to a width wider than the width value supplied to pdf_show_boxed() it will cause a seg fault because it does not know where/how to wrap the lines.

I do realise that pdf_show_boxed() is deprecated and that the problem is almost certain to be with the underlying library.

Reproduce code:
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$string="A string with a lot of unbroken characters QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ";
pdf_show_boxed($pdf,$string,$lmargin,$bottom_margin,$width,$height,"left","");

Expected result:
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I would expect pdf_show_boxed to break the string like so:

A string with a lot of unbroken characters
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ

Actual result:
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Segmentation fault