Button can be added to the surface and connected to a buttonhole to be locked.
2D View > 2D Menu > Button
Open 2D view, click on the 2D menu, then select Button
Select the desired button type via UI Panel > Properties > Button Properties.
Use the Button cursor to click on a desired location on the surface in 2D view to create a button.
Select the button via Button Selection Mode to move in 2D and 3D views.
Double-click the desired button type to apply via Button Selection Mode (UI Panel > Properties > Button Properties).