What’s the difference between autocomplete and dropdown history?

One shows things that might be, the other shows things that were. Both of them try to help you type something, but they operate differently (and look confusingly similar).

Let's take the second case first. Dropdown history, like you see in the Run dialog, common file dialogs, and the Internet Explorer address bar. The cue for dropdown history is a button with a downward-pointing arrow on it. When you click it, a list box with a scrollbar appears. Dropdown history shows you what you already typed into the dialog previously, and its contents are independent of what you've typed so far.

Autocomplete tries to guess what you're typing based on an existing database, typically files on your hard drive or web pages you've visited. The autocomplete dropdown is a popup window that filters itself as you type.

Since dropdown history remembers what you actually typed, the Run dialog history can remember command line arguments. On the other hand, autocomplete is based on what's on the system and what web sites you've visited, so it can suggest things you've never typed. Type "C:\" and an autocomplete window appears with everything in the root of your C drive. On the other hand, autocomplete can't remember command line arguments since that's not what it's drawing from.

Comments (5)
  1. Gary says:

    Dropdown history can often have a little bit of autocomplete thrown in for good measure. The Run dialog is a good example, where if you type ‘C:’ you’ll see other entries starting with ‘C:’ in the drop down list that you’d typed previously, as well as all of the subdirectories that exist in ‘C:’.

  2. Dan McCarty says:

    From a user-interface standpoint, autocomplete is a good example of one of the worst features NOT in windows: it doesn’t store its previous size.

    On my system I run two 1024×1280 monitors. Assuming that the average user just has a single 1280×1024 display, the autocomplete list in the run dialog still takes up less than 2% of the available screen space.

    This is just plain silly. The size translates to about 7 list items, and if the mouse hovers over either the top or bottom two it scrolls at hyper-ludicrous speed up or down.

    The autocomplete list in IE suffers from the same size issue. When trying to find a site I’ve been to before, the first thing I do once the list has dropped down is to grab my mouse and size it to fill about half the screen, then continue typing.

    (Another problem with the auto-complete list is that the list items aren’t selectable with Tab, but that’s minor compared to the main issue.)

  3. Andreas Haeber says:

    "(Another problem with the auto-complete list is that the list items aren’t selectable with Tab, but that’s minor compared to the main issue.)"

    Have you tried the up/down arrow keys?

    Or maybe I misunderstood what you’d like to do…

  4. Dan McCarty says:

    Andreas: As a keyboard user, using Tab means that I don’t have to move my fingers off of the home keys. The up/down arrows (not the ones on the keypad) work fine, but using them means moving my right hand (and eyes) over to the right. It shifts my focus from the task at hand.

    It’s no big deal, but Tab is so much easier, esp. if you’re used VStudio’s auto-complete feature.

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