To elaborate a bit on eibwen's reply, the answer depends on what you mean by "actually contains text". Given that you have the full text content (if any) from the widget stored in $data, you just need to choose what conditions are necessary and sufficient -- pick some condition like:

  $data =~ /\S/   # must contain a non-whitespace character
  $data =~ /\w/   # must contain an alphanumeric character
  length( $data ) > $minlength  # must be at least this long
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I'm sure you can come up with others that are more relevant to your needs. The point is to apply the test to $data, not to the widget.