Graph widget. Collapsed multiselect fields.

In graph widget form collapsed datasets accordion also collapses multiselect fields. When you click on this collapsed multiselect, it expands, but is not focused for typing. And this adds some confusion.

Steps to reproduce:

1. Add new widget
2. Select Graph widget
3. Add hosts so that they are transferred to a new line in input.
4. Click on "Add new data set"

Result:
Multiselect input collapsed to one line input. Clicking on collapsed multiselect is not focusing the input element.

Expected:
If multiselect has data, then clicking on collapsed multiselect should expend it and focus the input field.
If multiselect is empty, then there should be a placeholder (with an input field). By clicking there, you should be able to start typing immediately.