If you right click on a 3D object in the catalogue you will see a context menu with Edit Snap Points.
This will allow you to add / remove how an object snaps to another object, usually a similar object.
Note that there are 2 kind of objects .solids located in the Construction elements / 3D Constructions and ,cyg located in the Objects catalogue. You can convert .solids to .cyg, by selecting the .solid and saving it into the Objects catalogue as a .cyg. To apply snap points to a .solid, convert it to a .cyg
To snap glass panels together you would need to create a glass panel...
1. Create a panel out of an object from Objects / Misc / Basic forms.
2. Drag object into 3D view, resize it and apply glass material to th eobject
3. Save the new object into £D Catalogue using Export / 3D Formats / 3D Object file, making sire only to export the selected object.
4. Now right click on the new 3D object in the catalogue and select Edit snap points, where you can add new snap points to your glass panel so that they connect together when dragged into 2D / 3D views.
