I have a form in which a user can select multiple tags via a pop-up window (multi-select with check boxes). The tags are maintained in admin/settings section. It is not a good experience if the user has to leave the form just to add a new tag. How can this be addressed? So far I have these options:
1) a button "add tag" in the pop-up. When the user clicks on the button the pop up window will show an area to enter a new tag text together with cancel & save.
2) In the form add a button "new tag" next to the "select tags" option. It would add a new tag but I think it is confusing to have select and new tag next to each other.
3) Use a new window for selecting tags instead of pop-up window. Then a new tag could be added via pop-up in this window.
Right now I would go with 1) but I don't really like any of these options. I have searched UX Stack Exchange but I have only found one similar question with one design option. Does anyone have different solutions?
Update
I came across this option. Adding something like this at the bottom of the list:
When some enters a new tag text and hits the plus sign then the new tag is added to the list with a check box (similar to gmail label structure) and this plus/new tag entry stays there for any additional entries.