Now you can use #GC# that replaces generated link code in JAVASCRIPT field. The #GC# code have window.open or window.location of created URL.
There should be possibility the same for generateing javascript code. Like #GCJ# where generator prepare like: B10FIELD.value = 'some value'; .... Maybe there should be new type of indicator where you set Open form in .... or it should be set to typ of field like "button submit"
Diff: