modify caption: iptc/xmp mismatch depending on workflow

[CameronD]

This was seen on XnView classic, v 2.13. (x64 Windows 7)

To reproduce: seems to be 100% reliable.

• The "Edit IPTC data" window has option "Update or create XMP" ticked:on.
• Create a caption, "write", and observe IPTC caption and XMP description match, as expected.

Then, try to update the caption, and using three different workflows, you get 3 different results:

1. Repeat, using the same "edit IPTC window", click "write" and both IPTC and XMP get new text.
2. From browser window, choose IPTC tab and edit text directly in the window. Select another file, to make XnView ask you to save file, and then IPTC is updated, but XMP remains the old value. This is the worst case, as other software may regard the XMP data as having priority over IPTC.
3. Open the image in a new tab, edit->metadata->edit IPTC data. Then edit the caption, select "Apply" and ctrl-S (save). This time, the XMP block is removed entirely.

For all these situations, the "Update or create XMP" remains selected, so the user will assume that IPTC and XMP will stay in sync.

[xnview]

ok, i'll check