Tool-tip for disabled selects

[obr42]

This was found specifically reviewing the dynamic choice work - may not be realistic to apply elsewhere.

When creating a say_specific_with_choices_argument command, when the page first loads the message selection is grayed out. You must first select an instance. The Execute button has a tool-tip that explains what must be done to enable the button. Would be ideal to have that sort of help to get the message select enabled.