Scrollbars in a modal panel

I'm working on a web application where we have a开发者_开发百科 modal panel/dialog popup to collect user data. The form within the panel has grown large and we've suggested splitting the form across multiple tabs, but our client has suggested adding scrollbars within the modal panel.

Are there usability issues with scrollbars within a modal panel? I believe it's a bad practice but I'd like other opinions.

Thanks,

Glen

Update: I'll explain the scenario in more detail. We have a search page where search result items can be saved (copied into a another area of the system). Additional information can be saved with this items (e.g. additional comments, assignment to other buckets - I can't get into any more detail than that). When a user wants to save a search result item, they can check one or more items and click a save button - that's when our modal panel popups.

Originally, the users were taken to a separate page and they followed a series of pages. Our clients felt this was time consuming, so we changed the page to use a modal panel.

I'm not 100% sure using a modal panel is the best design, but that's what we have now. I welcome any other ideas.

Well, I gotta ask, if you have a modal form that's so long, shouldn't it be made into its own page?

I mean, the whole point of modal dialogues is to tell the user something he needs to know (which are usually disregarded and are annoying) or to get some information from the user that is necessary before proceeding.

You say your form is for gathering user input. If it's something the user must enter before proceeding (as in a part of a checkout flow or something like that), then I would say it's probably best to dedicate an entire page to the flow.

If it's something that's more of a "log in here before proceeding with what you're doing" kind of thing, again, I think it would make more sense for it to be its own page that brings you back to the page you were on before you entered it once you're done filling out the form. That's how the Stack Overflow human-verification page works.

If it's something annoying like "give us your feedback about the site", then it shouldn't be modal at all but rather an easily-dismissed (dare I say it?) pop-up window.

Modal dialogues really should be kept as brief as possible. If brevity is impossible, and the dialogue really must be modal, then I think it would make more sense to create a flow of pages that must be filled in before the next one can be accessed. Like a checkout: you need to add products to a cart before adding shipping information, and you need shipping information before you can determine the cost of the shipment. That kind of thing.

But without knowing the exact nature of your modal dialogue I can't tell you exactly which way would be best.

EDIT: Aha! Your clients felt this was time consuming, eh? This is the type of situation where you should do a very quick and dirty live usability test to see which way is actually better. Grab some people from down the hall, show some of them the modal way (with scrolling) of doing it and show others the old (non-modal) way of doing it and see what they have to say.

(Ideally you are recording the session and the screen, and you make sure to not let your own personal preferences show through. Just ask them to use the system while you watch to see how well they perform the task. Use the recording to time both methods to see if one way really is faster than the other.)

You shouldn't ever make a usability decision that goes against the norm (the norm in this case being "large forms merit their own pages") without making sure that it actually is more usable the abnormal way. When it comes to usability, the norm is usually the norm because it's usable (but not always, which is why you must test). If the client fights back, you'll at least have evidence that they're going against hard empirical evidence that what they want is silly.

Ultimately, though, the clients are the ones paying the bills. If you can't get them to see reason then you'll have to make the most of what they tell you. If the form must be in a modal dialogue, then you can at least try to hide non-essential fields under the fold (if there are non-essential fields) so that the majority of users will never have to scroll.

Make sure the buttons to submit the form (or whatever it is that you need to do with the form) are visible no matter where the user has scrolled. A really bad idea would be to put all the required fields at the top and then force the user to scroll down anyway to hit the submit button. That's just rude.

It seems to make sense to put a modal window here--I assume you're doing it as a layer on the page. But what it sounds like is that it's getting crowded, and you're looking at ways to manage the ever-increasing array of UI elements.

To answer your initial question about scrollbars, no, they are not verboten. However, as another responded asserted, you should never design action UI elements within the scrolling area.

It sounds as if some good user research could be useful here. What items are important to users. Which items are required and which are optional? Can they be categorized?

Some people suggest that tabs are useful for categorization when the number of UI items overflows a dialog box. In this case, though, I think this would be a bad idea. This isn't a setting category of dialog box, but more of a confirmation/selection/entry dialog where users will save whatever is entered and chosen. There's a good chance with tabs that users would miss the tabs and miss entering information. And if something on a "back" tab is required and a user doesn't go there, then you have a really poor error experience.

One of the things about scrolling is that it is easy for users with mice. they have the option of either clicking on the scrollbar or (for many) rolling a scroll wheel.

One thing you may not have considered, especially if some things that users can enter or choose are optional, is to create sections within the dialog box that can be collapsed and expanded. Sections with required elements would be expanded by default and sections with optional elements would be collapsed by default. If expansion of a section adds a scrollbar, that addition to the UI is obvious to users.

Of course, you may have to figure out how all this would work for people who have only keyboards, who have disabilities, and who might be accessing this on a mobile device.

I don’t think a tabbed panel is fundamentally better or worse than a scrolling panel. Each has advantages in different situations. However more important in your case is this: If you need tabs or scrolling then your panel is probably too complex to be modal. The more information input in a modal panel, the more likely a user will need to go somewhere else to get an answer, and the more work you throw away if the user decides they must go somewhere else for any reason.

The solution is to move as much information as you can out of the panel and onto the parent page/window. Let users enter the “additional information” right onto the search results page, allowing them to explore the results to help them decide on the information. Since the additional information apparently consumes a lot of space, make its controls show-able and hide-able, but always preserve user inputs between hides and shows. I think it’s okay to either tabs or scrolling to keep the footprint small. Additional information about a single search result should go in controls next to that search result, rather than in a separate panel.

The modal Save panel should only include a few controls that are instrumental to saving, such as the filename and location, and maybe the file type. If all the information is instrumental to saving, then make the save panel modeless. Who says you can’t?

Putting all the save information on another page is not much better than a modal panel, since that is also effectively modal, in the sense that the users can’t go somewhere else without losing their input. Even if you take steps to preserve users’ inputs to the page if they go to another page, most web-abused users will think they might lose their input, so they won’t try.