Keyboard navigation on multiple dropdown #1787

Hi, there doesn't seem to be a way to get out of the dropdown selection on a multiple-selection dropdown just by using the keyboard.

Both tab and return keys are bound to the selection of items in the dropdown list. Looking a jsuites dropdown, tab simply moves the selection on to the next form object (which is the expected html behaviour) but in the spreadsheet I would expect tab to complete the selection. As it is, unless I'm missing something, once you have a dropdown open the only way to complete it is clicking outside the dropdown with the mouse.

Thank you!