Modal popups - usability

Question

What are the cases where you'd use a modal popup ? Does it interrupt the user's flow, if it all of a sudden opens up in his face ? Would you avoid modal popups in general ? or when should one be careful of using them ?

Edit:

To be a bit more specific, the situation here is this :

I have a menu on the right, (VisualStudio style) when the user wants to add an element, should I expand the menu down and let them select something from it there, and then have to press the OK button, or display a Modal popup forcing them to select.

(the selection step is mandatory.)

Answer 1

IMO, avoid them for anything but stuff that you're absolutely sure requires immediate user attention. Otherwise, they just interupt the flow for no good reason

Answer 2

I don't think avoiding modal popups is usefull. Think about confirmation on closing unsaved work, fileopen dialogs, and such sort of things.

I think you should not show them all of a sudden, when the user is busy with something else.

Answer 3

From Wikipedia:

Frequent uses of modal windows include:

• drawing attention to vital pieces of information. This use has been criticised as ineffective.

• blocking the application flow until information required to continue is entered, as for example a password in a login process.

• collecting application configuration options in a centralized dialog. In such cases, typically the changes are applied upon closing the dialog, and access to the application is disabled while the edits are being made.

• warning that the effects of the current action are not reversible. This is a frequent interaction pattern for modal dialogs, but it is also criticised by usability experts as being ineffective for its intended use (protection against errors in destructive actions) and for which better alternatives exist.

Answer 4

Minimize. Use the status bar or some non-in-your-face mechanism of notifying the user.

You should be careful when you want to have automated tests. Modal dialogs love playing "show stopper".

Answer 5

To be a bit more specific, the situation here is this :

I have a menu on the right, (VisualStudio style) when the user wants to add an element, should I expand the menu down and let them select something from it there, and then have to press the OK button, or display a Modal popup forcing them to select.

(the selction step is mandatory.)

Answer 6

Personally, i think that modal pop-ups can always be avoided. The most common use of a modal pop-up is to indicate errors, or seek user input to proceed. Both of these actions can be accomplished "inline", i.e., by creating suitable actions on the same page itself without a modal pop-up.

E.g. errors in a text field input can be indicated by making the background red, or by making a small error icon next to the field, and the error text below it.

Pop-ups are always an irritation to a user, and in my opinion can be replaced cleverly without losing any functionality at all.

EDIT: In your situation, a simple solution would be to disable the commit button till the user has made a selection. This will ensure the user hits OK only after a selection is made

Answer 7

If you do go the modal popup route, please please add a delay before input is accepted. There are few things as annoying as typing in some application and seeing the tell-tale flash of dialogue box that implies something popped up, accepted whatever random key you happened to be pressing at the time as its input and gone off to take some random action.

Answer 8

Modal dialogs have been condemned by usability experts for a long time because of their disruptive nature regarding user workflow. See, for instance, Jef Raskin's "Humane Interface" book for discussion of modeless interfaces.