Copy the clicked term or text to the point. Insert modes are recognized. (`{(c-w)(m-w)(c-i)}', `{(c-r)(m-r)}', `(c-u){(c-r)(m-r)}')
See also `(c-c)' and `(c-a)(c-c)' for when you can't select the desired insert material with a single mouse click.
Special Cases:

Text to text:

Insert the whole text of the clicked text area to the point.
This is good for copying binding var text, for example.

Empty simple text operator to simple text operator (such as [text], [variable], or [word]):

Change the operator.