tinyMCE.getWindowArg is not a function

I recently updated two installations from 0.9.x to 1.0.6.

When trying to browse files from the TinyMCE link editor I get a Javascript error:

tinyMCE.getWindowArg is not a function

var win=tinyMCE.getWindowArg("window");
index....21&a=27 (line 736)

and no browse windows open.

Any ideas?

Thanks,
David.