[Enhancement]: multiple labels in input && keep open

[jahglow]

Hi, If a paper-listbox is used inside the dropdown, it's possible to make multiselect, though the paper-dropdown menu doesn't allow staying open if it's a multiselect (can't set this attribute or property, have to call .open() which gives this bouncing opening animation, which is annoying) and if an item is unselected, the paper-input is cleared, though it'd be a nice-to-have feature to calculate items selected and if they are more than 0, show them as comma-separated list (trimmed with ellipses) or as an option, to display a number of items, like (6 items selected) with configuarable text.

[phlbrz]

Hello,
A list of chip in the input would be interesting also.
https://www.google.com/design/spec/components/chips.html