Answers for "flutter outline shows nothing"

flutter outline shows nothing

Move the mouse to any widget and Press Ctrl (or command on macOS)
and click on that widget.
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After this step, your Flutter Outline will be enabled and showing widget tree

flutter outline nothing to show

press Ctrl and click one othe widget in dart file 
this should show the tree

flutter outline nothing to show

right click in the file and select 'reformat code with dartfmt' 
it will format your code and then left click in the file and 
select dart outline.