The approach taken to address this issue involved a custom implementation of IWizard and a simple WPF dialog. While I've created several of these in the past, until now it never seemed practical to create anything that could easily be reused.
There is now a NuGet package with ID MultiProjectWizard that can be used to provide multiple templates in a single VSIX without having to give up Online Template search functionality. Here are the steps (Note: These steps assume that you are using SideWaffle, though this NuGet package has no dependency on SideWaffle):
1. Setup your solution as if it were a multi-project template by placing each template in it's own folder with the *.vstemplate file named as MyTemplate.vstemplate. Include an _definitions folder in the parent folder and create a <language>.vstemplate file within it. See https://github.com/fsharp/FSharpCommunityTemplates/tree/master/VisualStudio/Mvc5/TemplatePack/ProjectTemplates/Web for an example of how to setup the folder structure.
2. Make the XML in the _defintiions/<language>.vstemplate file similar to the following and update the TemplateData appropriately.
3.Update the WizardData/Projects child elements appropriately. Each element represents one of the templates that was included in it's own folder in step #1. Here's a description of the attributes for the ProjectInfo element:
- folderName = This is the name of the folder created in step #1 that is associated with the template. The IWizard implementation will look into this folder and try to find a file with a name of MyTemplate.vstemplate.
- displayText = This is the text that will display in the WPF window for this particular template.
- icon = There are two options for icon: "FSharp" and "Generic". If you choose F#, then the icon for that template with include the text "F#", else it will not.
4. Install the MultiProjectWizard NuGet package. Note: This package includes DLLs such as EnvDTE and EnvDTE80. If your project already includes these DLLs, then you may need to remove the duplicate References after installing this package.
5. Lastly, add the MultiProjectDialog.dll and MultiProjectTemplateWizard.dll files as Assets to the source.extension.manifest file (as an Assembly with "File on filesystem" as the source):
You can now try out your template. If all has gone well, you'll see a screen that looks something like this: