Taborca's library requirements
Poppler 0.11.1 or newer
Poppler already had a convenient Qt4 binding. Efficient thumbnail support in Taborca depends on being able to read the thumbnails embedded in the PDF, though, so it was necessary to add this feature to the Qt4 binding. (Other PDF tools, even the commercial one, don't bother reading embedded thumbnails anymore. The assumption seems to be that CPUs and/or GPUs are fast enough to generate thumbnails for every page in a PDF, in the background. In practice, it can take a longish time for a large PDF, though. I don't want to wait for that when I know the PDF already contains embedded low-quality thumbnails. They are good enough for the the drag-and-drop functionality that I wanted to achieve.)
My changes to implement Page::thumbnail() have been committed to the source tree as of poppler version poppler-0.11.1. So you will need that version or a newer one to link Taborca.
Saving a PDF with different page order
Poppler does not do that yet.
Qt GIF plugin
The ability to save a GIF file with comments depends on this plugin. Due to the fact that some image formats support comments and some don't, Taborca should gracefully degrade if your Qt installation does not support comments in GIFs or does not support GIF at all. (Image export will still work with other formats.)
Qt 4.5.x or newer
Taborca has been built only with Qt 4.5.x so far. It may work with some slightly older versions, too.
Will be used for OCRing text within designated boxes. Not implemented yet.