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<p>Hi,<br>
<br>
The attached PDF file, "Labels_and_Languages_3_OC.pdf", clearly
reveals a bug in okular: some graphic objects are not erased when
switching between mutually exclusive Optional Contents
(implemented via the RadioButton group).<br>
<br>
This PDF demonstrates the "Optional Content" feature... When
opening it with any browser, you can open the layers and choose
one language among three available ones (there are mutually
exclusive). Most of PDF browsers (Adobe Acrobat Reader under
Windows, Evince under linux, ...) behave well. The problem comes
when using okular: when switching from one language to another,
the old active PDF object is not erased, and all texts are
overwritten on the display.<br>
<br>
This bug appeared for me since Ubuntu-17.10 (therefore for
okular-1.1.3). Previously (under Ubuntu-17.04, okular-1.0.3), it
was correct. The bug is still present in okular-1.6.3 under
Ubuntu-19.04.<br>
<br>
The PDF has been generated by my own graphic library Muesli. You
can open it with any text editor since it uses only ASCII
characters. To my knowledge, it is standard compliant: 'mupdf'
doesn't claim about any errors, and the "PDF Tools Online"
validator (<a class="moz-txt-link-freetext" href="https://www.pdf-online.com/osa/validate.aspx">https://www.pdf-online.com/osa/validate.aspx</a>) returns
nothing special about it: <br>
<i>Validating file "Labels_and_Languages_3_OC.pdf" for
conformance level pdf1.5</i><i><br>
</i><i> The document does conform to the PDF 1.5 standard.</i><i><br>
</i><i> Done.</i></p>
<p>Regards,<br>
Édouard Canot<br>
</p>
<div class="moz-signature">-- <br>
Édouard Canot<br>
tél: +33 (0)2 23 23 53 77<br>
Institut de Physique de Rennes<br>
CNRS, Université de Rennes<br>
Bât. 11A, bureau 129<br>
Campus de Beaulieu, F-35000 Rennes
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