at a glance, you can't know, you either have to read the title in the tab, but if the tabs are from the same site then they might have similar titles so that won't work. you need to change the colour of the current active tab in the drop to be more obvious, like make it green or blue or something different.
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or add an outline around the current tab (like as shown), anything is better than what is going on in the app currently
yes to this