Right, have finally reached this task - dragging and dropping a qrcode image file to decode into the box on the right works fine, but using the Decode -> Decode from File button does nothing. I can confirm that https://code.launchpad.net/~qr-tools-developers/qr-tools/trunk revision 26 does not have this problem (and this dropdown button has been split into two separate buttons, so it seems to have been updated a little in general).
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