When you create a new Detail or Worksheet viewpoint using a polygon input method, the resulting drawing will show the Boundary as a dashed line. If you do not want this boundary included in the Drawing window, disable the relevant checkbox in Options > Work Environment > More Options.
Relevant topics
Update Detail/Worksheet Marker Boundary
If you redraw the boundary of a source detail or worksheet marker, any markers linked to this marker’s viewpoint will not be updated until ...
Worksheet vs. Detail
While creating a Worksheet based on the source model is similar to creating a model-based Detail, the Worksheet is optimized for creating partial ...
Worksheet and Detail Tool Settings
The following settings work essentially the same way for the Worksheet and Detail tools.
For a description of generic settings common to all ...