[JimmXinu]

@Pachuqismo,

You want only a list of all the tags in the library? Without any link back to the books they are attached to?

I believe I ran across a way to get that a while back, but it's manual and a little weird:

1. Go into Calibre's Preferences -> Adding Books -> Adding Options(tab) -> Rules to Filter tags read from metadata(button).
2. Add Rule(button)
3. Click the button to the far right of the dialog, tooltip is "Edit the list of tags with the tag editor"
4. Select all tags in left list(ctrl-a), click the arrow in the middle to add them to the right list
5. Click ok
6. Now copy the list of all tags in your library from the text edit field
7. Cancel the Edit Rule to not save it and back out of preferences.

Regardless, I will not be adding such a feature to this plugin. I don't believe it fits with the plugin's function.

If you haven't, you should also look at Job Spy plugin, which has a ton of features beyond what it's name suggests, including lots of metadata management functions.

If nothing else, DaltonST is apparently more open to adding unrelated features to a plugin.