I noticed in the flash version of 2.7.3. that when
'settings.attributes=link' AND
'thumbnails.thumbnail.click=link' AND
the Link-field of an image is EMPTY that the image does not open when the thumbnail is clicked on.
It does open when the image has a link-field assigned.
You can see an example of this in a clean v.2.7.3 installation where I only changed the settings as mentioned above.
In the second and third picture of the folder 'Pictures 1' the thumbnail does not open the image.
In the first image (the lighthouse) I put the link #/content/start/ and this one does follow the link to the start-folder.
In the default settings everything is allright and the images do open after clicking on the thumbnail.
Also when the maincontroller 'Togglethumbnails' is used, the images do open.
Was the Link field one of the Custom fields that now support multi-language?
Link to the test-gallery:
http://www.martinbroeze.nl/g3/