OpenXML Filter: styled text parts of PowerPoint documents should be extracted as modifiable ones

Styled text parts of PowerPoint documents should be extracted as modifiable ones if they can’t be translated for some reasons (hidden, excluded, etc.).

The corresponding code snippet of net.sf.okapi.filters.openxml.PowerpointDocument#nextPart:

if (!isTranslatablePart(entry)) {
   if (isModifiablePart(contentType)) {
      return new ModifiablePart(this.generalDocument, entry, this.generalDocument.inputStreamFor(entry));
   }
   return new NonModifiablePart(this.generalDocument, entry);
}

As styles can be amended on merge due to the font mapping process being applied, there may appear some losses in this regard.

So, it would be better to make sure that all excluded or hidden styled text parts do not become “NonModifiable”.

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