Make tabs stateful. I.e., if you navigate away from a tab and come back you should come back to the state in which you left the tab. Clicking on the tab again should reset the tab state.

[monsieurtanuki]

cf. #679 (comment) by @jasmeet0817:

• Navigation bar becomes sticky
• If the user goes into a tab and clicks around (example: opens the product page from history tab), he is still in that tab, just browsing
• Tabs are sticky, so lets say a user is on the "Product page" from the "History tab", he clicks on "Preferences tab", then clicks back on the "History tab", he will land on the "Product page" he was recently viewing, rather than on the "history page". Tapping again on the History tab will take the user to the "History page". This behavior is akin to a few other apps like Gmail/parts of GMaps etc.
• When the user opens the app, the first tab displayed to the user is always the Scan page.