Working with markers is mostly similar to the procedure described in Section 5.9. The differences are as follows:
To drag a marker, locate the cursor on the circle in the middle of the marker. If the image scale is relatively small, the circle size may exceed the marker size.
If the marker is on a surface currently hidden behind other tissues, only the circle in the middle of the marker will be visible, and the marker itself will be hidden. If you drag the marker, it will be moved to the model surface that is currently visible. The line marker in this situation is not visible.