The following works fine in TL13, producing a PDF with the expected rectangle full of colored balls under the TL viewer, Sumatra PDF viewer, and Firefox, as it did under the prior MKIV beta (2014-06-01). Under the current MKIV, it produces a PDF that displays no image when viewed with Firefox or Sumatra PDF, but shows an irregular blob of colored balls (which might be cropped to the expected triangle) when viewed with the TL viewer or Chrome.
\useMPlibrary[dum]
\starttext
\externalfigure[xxx]
\stoptext
So, I would suppose that something has changed in the way the image is put into the page. Can somebody suggest an option to reverse this behavior, either in ConTeXt or in the viewers?

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Rik Kabel