Sharing custom templates
Chapter 6, Creating Custom Master Shapes, includes some information about custom templates and should be read in addition to this section.
Templates are just Visio documents with a VSTX, or VSTM, extension that tells Visio that the default action is to create a new document based on it. The template document may contain no Masters in its Document Stencil, or it could contain any number of custom Masters. For example, a custom version of the dynamic connector Master is found in several of the Microsoft Visio-installed templates.
Templates do not need to include docked stencils, but they often do. The docked stencils can be ones that are part of the Visio installation, or they can be custom stencils.
The preview image of a Visio document is created from the shapes that are on the first page. Therefore, a preview image of a template can be created by adding some shapes to the first page.
However, the default image created is not very sharp, but this can be improved....