Memengo™ Community and Support

Basically what I would want is the clickable letters on the right side of the card lists, which is available in some applications. An example of this can be seen in the contacts application when you are on the list of users, you can easily jump to a specific letter simply by tapping it on the right side of the screen. Another example is in the facebook application on your friends list.

The reason this is useful is because if you have a folder with many accounts, it would be easier, faster, and just a better overall user experience if you didn't have to rely on the keyboard or  a lot of scrolling to get to the card you want. 

From what I understand, if you implement the feature, it might require you to have the letter headings in the main list. I would recommend only showing the group headings when there are 6 or more items (which is exactly how the contacts app works), because if there is a small amount of items, you can easily get to the item you want and the group headings will just pollute the UI. 

As a side note, I've seen some people implement the letters on the side in a weird way. Instead of always having the letters A-Z visible, they only list the letters that actually exist in the list. This renders a weird looking UI that would just confuse more than help. One of the reasons it's confusing is because of the wide spacing between the letters. The other reason is that you only see a few random letters instead of A-Z, so it's not very easy to know why they are there. So just be sure that when you implement it, you include all letters, even those that don't have any cards for them. 

At first I was thinking that it should be a setting, but I think it makes more sense not to confuse the user and just include it by default kind of like how the contacts application doesn't let you choose to have it or not.

The only problem I can think of is the All Folders list which combines all the cards in one list and has the group headings with the name of each folder. One way I thought this could be solved is to not group the cards by folders. Basically combine all the cards from all the lists and only then sort them. This way the groups can now be the letters A-Z, and each group might contain cards from different folders. If someone does want the folder group feature, they could just go to the specfic folder they were looking for instead of using the All Folders list.