if the mouseChar is empty then select the mouseCharChunk
The first and second character numbers in the return value are always identical, unless the mouse is over a field but there is no text under it. In this case, the mouseCharChunk returns a [[chunk expression]] of the form char charNumber to charNumber - 1 of field fieldNumber, indicating the start of the mouseLine. For example, if the mouse is over an empty field, the mouseCharChunk returns char 1 to 0 of field fieldNumber.
See also: mouseChar (function),charToNum (function),mouseChunk (function),mouseLoc (function),clickCharChunk (function),mouseControl (function),mouseText (function),mouseLine (function),mouseMove (message),lockText (property),