Not sure if this is widely known but apart from simply combining CaseComplete shapes and adding them back into a library you can also import shapes from Visio into your own libraries. The properties looked similar in CC and in Visio so I thought "I wonder if this will work" and in general it does. Not all shapes will work but this is how you do it.
1. Open Visio and pick your favorite stencils; I needed UI elements to create UI diagrams to link to the UC's and Packages in order to create common shape libraries for my client in order to get threm ready for a large project and to promote standardisation of business analysis documentation.
2. Drag all the stencil shapes you need on to the Visio page - anything with a label you need to delete the actual label text.
3. Select the Visio shape and choose copy
4. Paste into a Case Complete diagram, if the shape looks the same as Visio's this will work, sometime the shape vanishes because of the way it's built, but 9 time out of 10 it's ok
5. Tweak as necessary then select the new item on your CaseComplete diagram and drag it onto your new custom shape library.
6. Give it a name "Webpage Browser", "drop down combo" whatever when the shape dialog appears
7. Repeat for all shapes that pull through
8. Save CaseComplete shape library
You can now give this to other analysts or use it yourself to reduce the number of times you need to use Visio and just build the diagram is CaseComplete as well as standardising your UI's in CC
HTH
Steve
...Steve