[scioto]

When iOS introduced the long press, that pretty much did it for me: I couldn't tell what user interface element did what when I pressed on it, so I tried tapping everything. And now we have to long-press on things to make them do other things. I can't spend time tapping then long-pressing on elements to do what I think or hope the app can do.

[layer8]

Apple should have established long press for the purpose of context menus in iOS, from the start. When I got my first iPhone around 2009, I was rather surprised that this wasn’t a standard convention, like right-click on the desktop. It seemed so obvious that that’s how things should work. Instead we now have long press for random purposes.

[euroderf]

A UI convention for "long-press-able" might be a start.

[layer8]

IMO it should behave like right-click (context menu) on the desktop, which generally doesn’t require an indication.

[mdaniel]

May I vote for ellipsis overlaid on one corner of the element?

  -------...-
  | Primary |
  -----------

unobtrusive, "..." indicates more was omitted in every context I can think of, and it can be any number of colors because it's so visually distinct (err, of course, except for the same color as the background, but if someone was that evil, we're right back where we started from in the "I dunno, guess" realm)

[grishka]

iOS didn't introduce it. Windows Mobile definitely had it before 2007. Not sure about Palm OS though.