Introduced with the original Mac OS X were dialog sheets:

alt text

As I understand (not being a Mac user) these sheets are modal, requiring user interaction in the current window, but not limiting the user elsewhere.

I'm just starting work on a new project where this kind of "limited-scope" modality might be very useful.

I like the idea that my users will be able to switch away from one activity to another without having to cancel partial results.

I'm also pretty sure I can emulate the look and feel with WPF.

But, should I?

What are the benefits and drawbacks of dialog sheets as seen in Mac OS X?
Might it be worthwhile to emulate these?

[I figure this might need to be a community wiki post - but I can't see the checkbox, probably because I've low reputation. Can someone flip the switch for me? Ta.]

  • I'm not sure I understand the difference between this (the way you explained it) and a modal dialog in any Windows application. Can you explain the difference? Commented Oct 20, 2010 at 18:27
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    As I understand it, a dialog-sheet is modal only for the specific window to which it's attached. In a multi-document application, the user is still free to switch to other documents and work on them. A normal windows modal dialog is application modal - the user has to deal with it entirely before doing anything else with the application.
    – Bevan
    Commented Oct 20, 2010 at 18:32
  • The Stack Overflow team have begun discouraging the use of community wiki and removed the checkbox. See meta.stackexchange.com/questions/392/… Commented Oct 21, 2010 at 0:32
  • See Apple's documentation on sheets. It explains how they work and when to use them. (But not, obviously, whether you should us them on Windows.) Commented Oct 21, 2010 at 0:44

4 Answers 4


Don't confuse your users, use Mac-style UI on a Mac and Windows-style UI on Windows.

The problem with having dialog sheets on Windows is that some people don't have any experience on Macs and don't care about UI widgets on other platform, so the dialog sheet in your application will be completely new to them - and they are likely to be a little bit confused and slightly annoyed (even if dialog sheets are actually superior to normal dialog boxes - and I'm not sure they are).

BTW, it's possible to have dialog boxes that are model only to their parent window and not the whole app on Windows - but I think having this is also a bad idea for exactly the same reason.

  • You make a good point - do things in the way that people expect, reducing the amount of learning people need to do to use the application. In my case, I'm dealing with an in-house application for a couple of hundred users who use it all the time. In Alan Coopers taxonomy, a sovereign application. I believe trading off some non-standard ideas for clear benefits in the user experience is viable in this context. In other situations - say, an application for sale online - doing this would be a terrible idea.
    – Bevan
    Commented Oct 21, 2010 at 19:39
  • @Bevan - just two points: 1. I'm not sure dialog sheets are more usable than dialog boxes, actually I suspect they are not 2. it will take more work than you think to implement this well, GUI widgets tend to have a lot of corner cases that have to be covered and a lot of subtle behaviors that have to be implemented -- those two pints lead me to suspect you are going to make a large investment in both development time and training time for no benefit.
    – Nir
    Commented Oct 24, 2010 at 15:37
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    @Bevan - maybe you should A/B test an initial dialog sheet implementation against a dialog boxes - my guess is that you won't see any user behavior changes between the two groups but I may be wrong (if you do that I'd love to see the results)
    – Nir
    Commented Oct 24, 2010 at 15:40

The drawbacks are the same as any modal interaction.

The benefit, compared to what Windows does, is that it's directly attached to the particular process's window. Often in Windows (and bad Mac apps like Lotus), an application window can be locked because there is a modal open elsewhere that one doesn't notice or is even able to find (a commpon problem for those of us using multi-display set ups with dozens of windows open at a time)


I honestly can't think of a drawback. I really like dialog sheets. My least favorite usage of them is when using an Open/Save dialog, as in the screen snapshot that you posted, but they generally work really well.

In our office, we even have an "alerts" cross-platform implementation using wxWidgets that uses native Mac dialog sheets on the Mac and displays a regular alert on Windows. The idea is to give the Mac app a more natural feel.


Correct me if I'm wrong. I haven't used a Mac for almost a year, but what I really found annoying was that I was able to move those "dialog sheets" when — for instance — I needed to see a couple of page numbers in the underlying TOC in the document I was about to print. (There may be a way to do this but I never found out.)

In general, I agree that dialog sheets and modal dialogs have roughly the same pros and cons (as stated elsewhere in this thread) but I found this little difference particularly annoying for my work process.

  • I would agree that using them for print dialogs is less than ideal.
    – DA01
    Commented Oct 21, 2010 at 14:18
  • If you need to see the document in a modal sheet, provide a preview.
    – bastibe
    Commented Oct 24, 2010 at 12:52
  • @BastiBechtold I guess a preview could do, yes, provided it was large enough to render the text readable.
    – jensgram
    Commented Oct 25, 2010 at 6:02
  • Remember that a modal sheet is meant to freeze the document while it is open. If you need more detail than can be reasonably provided in a modal sheet or if you need the possibility to continue to edit the document, a modal sheet might be the wrong UI for the job.
    – bastibe
    Commented Oct 26, 2010 at 7:31
  • @BastiBechtold I totally agree with you. I was just addressing OP's question "What are the benefits and drawbacks of dialog sheets as seen in Mac OS X?" with a specific case where I found it to be a drawback. With a modal dialog I would have been able to see the page numbers (I just needed to move it, not manipulate the document per se).
    – jensgram
    Commented Oct 26, 2010 at 7:43

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