SUMMARY
Outline selection tool doesn't use shift to add and alt or control to remove area. also can't be moved.

STEPS TO REPRODUCE
1.Select the outline selection tool
2. Make a selection
3. Try to add a new selection área with Shift
4. Try to move the selection as you do with square selection for example.

OBSERVED RESULT
You can't see the symbol for Add a new selection "+" or "-" to remove area from selection
You can't see the cross to move selection and neither you can't move the selection.

EXPECTED RESULT
Same result as you have when use elliptical selection or Square selection or poligonal selection.  



SOFTWARE/OS VERSIONS
Windows:  10
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
"Lasso technique " is very used in concept art or speed Painting. Because You can uuse selections as stencils this way. 
You draw very fast a selection add areas to selection or remove as you want. Then you Paint the selection with textured brush or gradients. Then you move the selection to another place and transform the selection to distort a bit and then Paint  using it as stencil. That gives a lot of detail fast with textured brushstrokes and hard edges.

Thanks a lot for your time.