One Map Stash Tab can store the equivalent of dozens of regular Stash Tabs and comes with the added convenience of an in-built sorting system. It's also possible to name your tabs and make them public for trading! If you have legacy maps from Path of Exile's past, you can right click on your Map Tab while it's empty to change what series of maps it is set to, as it can only hold maps from one series at a time. Different series are indicated by different background map art. Let's take a look at some people's view of this images.
1) Just give the maps the same background like they have in the atlas. Highlighted when completed, circled when bonus applies. That would be nice and intuitive.
2) Then we might as well directly apply maps from the atlas. Maps you have in you stash are highlighted on atlas and you can use chisels/chaos orbs to upgrade your map right there.
3) OK, so look at it like this. They have an idea, they like it, they do it, it's in the game, they promote it, and money/people come pouring in. They could have sat around an extra few days/week/month thinking about all these little details, deciding which ones are worth implementing, and actually doing them, or they could throw it out there and let the community make suggestions like this, giving them free feedback on what's wanted.
Then, when they follow some of the easier parts of what's suggested, they're praised as heroes and more money/people come pouring in.
It may sound cynical, but it's a better business move to do it the way they do things.
4) This reminds me of Diablo 3 where you can store the power of unique items in a thing called Kanai's Cube. You only need to extract the power once for each unique. Problem was that people would lose track of which unique powers they had and which they didn't. The community asked for an indicator of some kind and we eventually got one. On a unique item with a power there was a small diamond next to the power that can be extracted, when the diamond is full that meant you already had the power.
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