The Lock Stencil feature protects a stencil from being overwritten by updates from D-Tools. If you have modified any of the stock Visio stencils, you may want to lock them.
1/ In the D-Tools SI window, click the Shapes tab, then click on the stencil you want to lock.
2/ Right-click and click Lock Stencil.
You will see the following prompt.
3/ Click Yes.
The stencil will now display in the Shape Tree with a lock icon next to it.
To unlock a Stencil, right-click the stencil and click Unlock Stencil.