When selecting multiple snuable media, the context menu should be more specific

[sthiel]

If there are different types of media selected, the context menu should indicate what will be affected but show all available options:

Create SNU (2 items) Open in SNU editor (1 item)

For the rest of the items, don't show anything and, as expected, default to all.

Rename should be visible, but disabled (a means to show it can be done, but nor with multiple items), perhaps with a qualifier "(only single items)".