Open the advanced editor: http://tinymce.moxiecode.com/example_advanced.php?example=true Select some text Click on "Insert/edit link" The link editor will open, but will be blank. "Null value" is logged to the JS console.
This appears to work right in development versions of TinyMCE, see for example http://tinymce.moxiecode.com/test/examples/example_full.htm
Closing since it is fixed in dev versions of TinyMCE (we already have a record of their blocking bugs that we are waiting on).