Currently, when we click to select a pre-defined saved value in the a field (stored in Options > Tag-Panel > Custom list values > Manage), we can only choose one value from the list. Consequently, if a field can have multiple values, we are unable to select more than one from the list.
For example, in the Artists field, if we want to add more than one artist's name, we need to manually type something like Artist1\ \Artist5\ \Artis9, even if the drop-down contains several pre-defined values.
So to ease this up, it would be beneficial to have a |+| button next to each field. Clicking this button would allow us to add multiple values, with an automatic insertion of \ \ after each already typed value. Additionally, clicking the button would also open the drop-down instantly, without requiring any extra clicks. As an alternative or an additional enhancement, the drop-down could also open automatically when we manually type \ \ , making it possible to perform the entire task using only the keyboard, without any mouse clicks.
To further streamline the process, an additional filter could be implemented, which would refine the drop-down list. For instance, if the artists list contains around 100 values, typing "m i c h a e l" in the filter would narrow down the list to display only the names containing "Michael".
I am suggesting this feature based on my workflow, and I am not certain if it would be equally beneficial to others. 