Streamline the Editing process from inside Online
You open a workbook in Excel Online. After review, you want to make a quick update, so you click Edit Workbook / Edit in Browser. But all you get is a popup that says you have to checkout the workbook, with a button to Continue in View Mode.
It's 2018. Let the system check to see if the workbook is currently checked out. If not, then check it out for me and let me make my quick edit and exit. If it is checked out, pop up a message telling who has it checked out, with a button to alert them.
Or at least add a Checkout this Workbook button to that pop up message to save yourself from having to go all the way back out to come back in.