We are designing the UI for a new line of business application. We have no real constraints and are free to design the UI as we see fit. The UI will be done in WPF and targeted for Windows 7, Vista, and XP Pro users.
Many dialog boxes contain OK and Cancel buttons in their lower right corner. Do you feel it is necessary to have this Cancel button or is the red X in the upper right corner sufficient? We are discussing this as we have been noticing more UIs that do not have cancel buttons, only the red X.
Not only you should add it but also make sure ESC is mapped to it.
Present the two designs to the customer - one with the "Cancel" button, the other without. See what their thoughts are.
Better still present them as partially working prototypes and watch them as they use the dialogs. If you ask them to perform a set of tasks and see if they have trouble when asked to cancel an operation.
Having said that, my preference is to include a "Cancel" button for the reasons others have mentioned:
Accessibility (especially as Esc should be mapped to it).
Convention (users will be expecting it).
Include the Cancel button. The red X is VERY hard to tab to. ;)
Include it. This is very common in other user interfaces. Give the user the choice of which to use; making it for them might make them annoyed with your interface.
Users are used to having standard GUI layouts - otherwise they get confused. They also have different ways of using the standard interface. Some people only use the X, some people only use Cancel. People usually ignore the one they're not using, but get confused if their one isn't present. So be safe and keep them both in - it should only be a one-liner function for Cancek anyway.
Include it!
From a user interface perspective, not including a cancel button might leave some users feeling like they have no choice, which is certainly not the case. Imagine the following simple decision scenario:
Warning: All of the files in the selected folder will be deleted. This action cannot be undone. Are you sure you would like to continue?
How silly would an interface be if the only option was Ok? Also, as noted above, on many platforms the Escape key is mapped to Cancel. It's also probably worthwhile setting a default button so that pressing the Enter/Space key doesn't inadvertently perform the action that cannot be undone.
+1 on including it. If you don't include it now and then need some different functionality on Cancel to Close later on, your users will already be used to automatically closing.
Just like we have 'ESC' button on keyboard, we need 'Cancel' in dialogs.
A matter of usability :-)
Include it. And please also make sure that you make sure that hitting the Escape key does the same thing as the Cancel button.
Also, just because you're designing from scratch, please don't throw out all convention. Take a look at MSFT's UX Guidelines for dialog boxes.
The red button is really for 'Close' rather than 'Cancel'. 'Cancel' canceling a running task. Use a 'Close' button instead. And yes include the 'Close' if there is a reason for people to click on it. The red button is quite difficult to click when you really want to close something quickly.
If you have that kind of freedom, consider eliminating dialog boxes from your application entirely, especially ones with the typical "OK | CANCEL" paradigm. Dialog boxes disrupt the flow of action and generally should only be used for things which absolutely require the program to interrupt the user.
You'll notice how disruptive they are in the web environment -- e.g., Stack Overflow only uses them when it needs to be able to OVERRIDE your action, e.g., when you navigate away from an unsubmitted answer.
Related
I have this link:
The Best Page
The ajax-populated and -revealed element that exists within the current page is an "enhancement" and has aria-hidden="true". It would be preferable for screen-readers and assistive tech to follow the link's href to the subsequent static page, rather than triggering the click handler (especially since the element that it will acts on is already hidden, as previously mentioned).
Will this behavior already take place or do I need to add something?
When pressing enter on a link, it does the same as a click, and it's a very bad idea to intercept the enter key in order to do something different.
There are keyboard users, perfectly sighted, who aren't using screen reader. These users will experience an unexpected behavior.
Screen readers may choose to send directly a click event, rather than keyboard events, even though enter has been actually pressed. So idem in the opposite direction.
There may be other ways to activate a link, other than click or enter: spacebar, tap on touch screen, assistive techs to click by winking the eyes, etc. How it should behave in these cases ?
By the way, you can't do something different based on whether a screen reader is used or not, simply because you have no 100% reliable way to detect it.
The questions you should ask yourself are:
Why do you want a different behavior between click and enter ? or between screen reader and normal users ?
Are you trying to work around inaccessible content, or do you have two versions of the same content (an accessible and a unaccessible one) ? In that case, it would be much better to have a single content and make it accessible. Rare are the cases where it's really impossible, and experience shows that the two versions are eventually going to be out of sync, more quicker than you think.
An Apply button is in many systems and programs, a common approach, which has its place (look and feel). But what is the recommended Hotkey for an 'Apply'-Button.
OK(Enter), Cancel(ECS), Help(F1), Apply(??)
Which Hotkey do you prefer?
Alt+A, I'd say. So simply use the normal accelerators (those prefixed with &).
As far as I know there are no default single-key accelerators in dialogs beyond those you mentioned already.
I reccomend you not to force the user to apply something. Try to apply the users input directly. This simplyfies your application because the user does not have to care about this. Anyway you have to give the user a feedback for his changes. Show him a "your input was saved" message (no message box). Try to avoid every step which is not needed. This makes your application or webpage more userfriendly.
Besides this, no user wants to remember "hotkeys" for thousands of programs.
If you really need a hotkey, then I recommend some ENTER like combination.
We can look the Apply as a semi OK, because the modifications are commited but the window stay open.
A semi ENTER can be for example a CTRL+ENTER or CTRL+ALT+ENTER, etc
I have a Cocoa application managing a collection of objects. The collection is presented in an NSCollectionView, with a "new object" button nearby so users can add to the collection. Of course, I know that having a "delete object" button next to that button would be dangerous, because people might accidentally knock it when they mean to create something. I don't like having "are you sure you want to..." dialogues, so I dispensed with the "delete object". There's a menu item under Edit for removing an object, and you can hit Cmd-backspace to do the same. The app supports undoing delete actions.
Now I'm getting support emails ranging from "does it have to be so hard to delete things" to "why can't I delete objects?". That suggests I've made it a bit too hard, so what's the happy middle ground? I see applications from Apple that do it my way, or with the add/remove buttons next to each other, but I hate that latter option. Is there another good (and preferably common) convention for delete controls? I thought about an action menu but I don't think I have any other actions that would go in it, rendering the menu a bit thin.
Update I should also point out that delete should be an infrequent option - the app is in beta so users are trying out everything. This is a music practise journal, so creating new things to practise happens every so often (and is definitely needed when you start out using the app), but deleting them is not so frequent.
Drew's remark is always your first consideration. All other things being equal, I'm not a fan of making deletion as easy as creation; it's a dangerous and comparatively rarer action, and the UI should reflect that fact. However, not having an explicit delete control can indeed lead to support enquiries (the same happened in MoneyWell after the minus buttons were removed). The issue is that you won't hear from the people who avoided accidental deletion by hitting a too-close-to-the-plus deletion control; those people are happy and quiet. You will, however, hear from those who can't immediately find a button to click for deletion, even though almost all of Apple's applications have no such control.
If you feel that you need explicit UI for deletion, I think you can find a middle ground. The problem with deletion controls is accidental triggering, and the conventional "solution" to that problem is a confirmation alert. The problem with that is how intrusive and jarring they are, because they're modal. iPhone OS can teach us a lesson here: you can make confirmation entirely contextual and non-modal.
Examples are row-deletion (swipe to put the row into its "are you really sure you want to delete?" state, which visually tends to slide a red Delete button into view), then interact again (by tapping Delete) to actually confirm the action. There's a similar model on the App Store whereby tapping the price button changes it into a Purchase button; it's essentially an inline, non-modal confirmation. The benefit is that if you tap anywhere else (or perhaps wait a while), the control returns to its normal state on its own - you don't need to explicitly dismiss it before continuing work.
Perhaps that sort of approach (non-modal change as a sort of inline confirmation) can get rid of the support queries by making deletion controls explicit, but also patch up some of your reasonable concerns about intrusive confirmation.
I would say this depends on how important deletion is to the particular task. Is it something that the user has to do often, or very rarely. If it is rare, delete should just be left as an Edit menu option, and perhaps as backspace (Why cmd-backspace? If you can just have backspace, you probably won't get as many queries.)
As with everything in interface design, my take is to apply an 80-20 rule. If something belongs to the 20% of most used functionality, it should be exposed directly in the interface. If it is in the other 80%, you can hide it deeper (eg in a menu, action menu etc).
A + button is definitely in the top 20% --- you can't do anything without it --- whereas a delete is usually not a common operation, and is destructive, so can probably better be hidden away a bit.
The usual solution to this problem is to put the [+] and [-] buttons next to each other (see, for example, the Network pane in System Preferences). I generally find those buttons large enough that I don't hit the wrong one by mistake, although I can see that potentially being a problem.
If that option doesn't suit you, maybe take inspiration from Safari: put an 'x' inside the selected (or hovered) item.
Since your app supports undoing of deletion, I would suggest that you err on the side of making deleting stuff easy (at the expense of making it too easy) and make it obvious that these mistakes are easily undo-able. GMail does a decent job of that.
HTH.
How frequently is delete needed? Does the data and the user's expectation encourage deleting this data often? (is it a list of tasks, for example)? If so i'd certainly include a contextual action menu, even if Delete was the only option.
Cmd + Backspace may be a little unusual for people too - I know it's used in other places on OSX, but those places also provide context menus to expose the delete - i'd be surprised is every user knows about Cmd + Backspace, so i'd probably change it to Backspace (you do have undo support, so you're covered there).
Finally, and hopefully I don't sound like a git, but it suggests that the built-in help doesn't offer enough guidance on this - might be worth revising it?
Matt gave pretty much the same answer I was going to write.
Note that when you delete the object, you should animate it away: this provides valuable visual feedback: the animation (about 1/3 of a second is good) is long enough to catch the user’s eye, and they’ll see the object disappearing. If the object just disappeared without animating, the user would notice that something had changed instantaneously in the list, but would be less certain what it was. The animation reinforces the meaning of the delete button in the user’s mental model.
This is inspired by the question OK-Cancel or Cancel-OK?.
I remember reading somewhere about the concept of switching OK-Cancel/Cancel-OK in certain situations to prevent the user from clicking through information popups or dialog boxes without reading their content. As far as I remember, this also included moving the location of the OK button (horizontally, left to right) to prevent the user from just remembering where to click.
Does this really make sense? Is this a good way to force the user to "think/read first, then click"? Are there any other concepts applicable to this kind of situation?
I am particularly thinking of a safety-related application, where thoughtlessly pressing OK out of habit can result in a potentially dangerous situation whereas Cancel would lead to a safe state.
Please don't do this unless you are really, really, really sure it's absolutely required. This is a case of trying to fix carelessness and stupidity by technological means, and that sort of thing almost never works.
What you could do is use verbs or nouns instead of the typical Windows OK / Cancel button captions. That will give you an instant attention benefit without sacrificing predictability.
NOOOOOOOOOOOO!
In one of our products we have a user option to require Ctrl+Click for safety related commands.
But startling the user with buttons that swap place or move around is bad design in my book.
NO. If you make it harder for the user to click OK by mistake and force them to think, they will still only think harder about how to click OK -- they will not think about the actual thing they're trying to carry out. See usability expert Aza Raskin's article: Never use a warning when you mean Undo. Quote:
What about making the warning
impossible to ignore? If it’s
habituation on the human side that is
causing the problem, why not design
the interface such that we cannot form
a habit. That way we’ll always be
forced to stop and think before
answering the question, so we’ll
always choose the answer we mean.
That’ll solve the problem, right?
This type of thinking is not new: It’s
the
type-the-nth-word-of-this-sentence-to-continue approach. In the game Guild Wars, for
example, deleting a character requires
first clicking a “delete” button and
then typing the name of the character
as confirmation. Unfortunately, it
doesn’t always work. In particular:
It causes us to concentrate on the unhabitual-task at hand and not on
whether we want to be throwing away
our work. Thus, the
impossible-to-ignore warning is little
better than a normal warning: We end
up losing our work either way. This
(losing our work) is the worst
software sin possible.
It is remarkably annoying, and because it always requires our
attention, it necessarily distracts us
from our work (which is the second
worst software sin).
It is always slower and more work-intensive than a standard
warning. Thus, it commits the third
worst sin—requiring more work from us
than is necessary.
[If you want a Microsoftish one, this one by a .NET guy on MSDN says the same thing!]
If you must use a dialog, put descriptive captions on the buttons within the dialog.
For example, instead of OK and Cancel buttons, have them say "Send Invoice" and "Go Back", or whatever is appropriate in the context of your dialog.
That way, the text is right under their cursor and they have a good chance of understanding.
The Apple Human Interface Guideline site is a great reference, and very readable. This page on that site talks about Dialogs.
Here is an example image:
(source: apple.com)
No, it doesn't make sense. You're not going to "make" users read. If the decision is that crucial, then you're better off finding a way to mitigate the danger rather than handing a presumed-careless user a loaded gun.
Making the "safe" button default (triggered by enter/spacebar/etc.) is a good idea regardless, simply because if they surprise the user then a keystroke intended for the expected window won't accidentally trigger the unexpected action. But even in that scenario, you must be aware that by the time the user has realized what they've done, the choice is already gone (along with any explanatory text on the dialog). Again, you're better off finding another way to give them information.
What I've done in some instances was to compare the time of the message box being shown with the time of it being dismissed. If it was less than 'x' amount of seconds, it popped right back up. This forced them, in most cases, to actual read what was on the screen rather than just clicking through it blindly.
Fairly easy to do, as well....
Something like this:
Dim strStart As DateTime = Now
While Now < strStart.AddSeconds(5)
MessageBox.Show("Something just happened", "Pay Attention", MessageBoxButtons.OK)
If Now < strStart.AddSeconds(5) Then strStart = Now Else Exit While
End While
At the end of the day you can't force a user to do something they're unwilling to do... they will always find a way around it
Short cut keys to bypass the requirement to move the mouse to a moving button.
Scrolling down to the bottom of the EULA without reading it to enable to continue.
Starting the software and then going to get their cup of tea while waiting for the nag screen to enable the OK button.
The most reliable way I've seen this done is to give a multiple choice question based on what is written. If they don't get the answer correct, they can't continue... of course after a couple of times, they'll realise that they can just choose each of the answers in turn until the button enables and then click it. Once again meaning they don't read what was written.
You can only go so far before you have to put the responsibility on the user for their actions. Telling the user that their actions are logged will make them more careful - if they're being held accountable, they're more likely to do things right. Especially if there's a carefully crafted message that says something like:
This is being logged and you will be held accountable for any
repercussions of this decision. You have instructed me to delete
the table ALL_CORPORATE_DATA. Doing so will cause the entire company's
database to stop working, thus grinding the whole company to a halt.
You must select the checkbox to state that you accept this responsibility
before you can choose to continue...
And then a checkbox with "Yes, I accept the responsibility for my actions" and two buttons:
"YES, I WANT TO DELETE IT" this button should only be enabled if the checkbox is checked.
"OH CRAP, THAT'S NOT WHAT I MEANT AT ALL" this button can always be enabled.
If they delete the table and the company grids to a halt, they get fired. Then the backup is restored and everyone's happy as Larry [whoever Larry is] again.
Do NOT do it, please. This will have no positive effect: You are trying to AVOID people's clicking OK instead of Cancel, by making them potentially click Cancel instead of OK (okay, they may try again). But! you might as well achieve people's clicking OK when they really want to cancel and that could be a real disaster. It's just no good.
Why not reformulate the UI to make the OK the "safe choice"?
The problem is better solved with a combination of good feedback, communication of a system model and built-in tolerance.
In favor of the confirmation mechanism speaks the simplicity of implementation. From programmer's point of view it's the easiest way of shifting responsibility onto user: "Hey, I've asked you if you really want to shoot yourself into the foot, haven't I? Now there is no one to blame but yourself..."
From user point of view:
There is a productivity penalty of having to confirm operation twice every time even though actual mistakes take up just a fraction of total number of actions, any switching of buttons, breaking the habitual workflow or inserting a pause into confirmation just increases the penalty.
The mechanism doesn't really provide much safety net for frequent users whose reflexes work ahead of the concious mind. Personally I have many times done a complex sequence of actions only to realise a moment later when observing the consequences that my brain somehow took the wrong route!
A better for the user, but more complex (from software development point of view) solution would be:
Where possible communicate in advance what exact affect the action is going to make on the system (for instance Stack Overflow shows message preview above Post Your Answer button).
Give an immediate feedback to confirm once the action took place (SO highlights the freshly submitted answer, gmail displayes a confirmation when a message is sent etc).
Allow to undo or correct possible mistake (i.e. in SO case delete or edit the answer, Windows lets restore a file from recycle bin etc). For certain non-reversible actions it's still possible to give an undo capability but for a limited timeframe only (i.e. letting to cancel or change an online order during the first 10 minutes after its submission, or letting to recall an e-mail during the first 60 seconds after its been "sent", but actually queued in the outbox etc).
Sure, this is much more initial work than inserting a confimation message box, but instead of shifting the responsibility it attempts to solve the problem.
But if the OK/Cancels are not consistent, that might throw off or upset the user.
And don't do like some EULAs where a user is forced to scroll a panel to the bottom before the Agree button becomes clickable. Sometimes you just won't be able to get a user to read everything carefully.
If they really need to read it, maybe a short delay should happen before the buttons appear? This could also potentially be annoying to the user, but if it is a very critical question, it'd be worth it.
Edit: Or require some sort of additional mechanism than just clicking to "accept" the very important decision. A check box, key press, password, etc.
I recommend informing the user that this is a critical operation by using red text and explaining why is this an unsafe operation.
Also, rather than two buttons, have two radio buttons and one "Ok" button, with the "don't continue" radio button selected as default.
This will present the user with an uncommon interface, increasing cognitive load and slowing him down. Which is what you want here.
As always with anything with user interaction, you have a small space between helping the user and being annoying. I don't know you exact requirements but your idea seems OK(pun intended) to me.
It sounds like your user is going through a type of input wizard in the safety app.
Some ideas as alternatives to moving buttons.
Have a final screen to review all input before pressing the final ok.
Have a confirmation box after they hit ok explaining what the result of this action will be.
A disclaimer that require you to agree to it by checking a box before the user could continue.
Don't switch it around - you'll only confuse more than you'll help.
Instead, do like FireFox and not activate the control for 5 sec. - just make sure you include a timer or some sort of indicator that you're giving them a chance to read it over. If they click on it, it cuts off the timer, but requires they click one more time.
Don't know how much better it will be, but it could help.
Just remember, as the man said: You can't fix stupid.
This will give me headache. Especially when I accidentally close the application and forget to save my file :(
I see another good example of forcing user to "read" before click: Firefox always grayed out the button (a.k.a disable) the "OK" button. Therefore the user have to wait around 5 seconds before he can proceed to do anything. I think this is the best effort I have seen in forcing user to read (and think)
Another example I have seen is in "License and Agreements" page of the installer. Some of them required the user to scroll down to the end of the page before he/she can proceed to next step.
Keyboard shortcuts would still behave as before (and you'd be surprised how few people actually use mice (especially in LOB applications).
Vista (and OSX IIRC) have moved towards the idea of using specific verbs for each question (like the "Send"/"Don't send" when an app wants to crash and wants to submit a crashdump to MS)
In my opinion, I like the approach used by Outlook when an app tries to send an email via COM, with a timer before the buttons are allowed to be used (also affects keyboard shortcuts)
If you use Ok and Cancel as your interface you will always be allow the user to just skip your message or screen. If you then rearrange the Ok and Cancel you will just annoy your user.
A solution to this, if your goal is to insure the users understanding, is:
Question the user about the content. If you click Ok you are agreeing to Option 1, or if you click Ok you are agreeing to option 2. If they choose the correct answer, allow the action.
This will annoy the user, so if you can keep track of users, only do it to them once per message.
This is what I responded to Submit/Reset button order question and I think the same principle can be used here. The order does not really matter as far as you make sure the user can distinguish the two buttons. In the past what I have done is used a button for (submit/OK) button and used a link for (reset/cancel) button. The users can instantly tell that these two items are functionally different and hence treat them that way.
I am not really for OK/Cancel. It's overused and requires you to read the babbling in order to say what you are OKing or Canceling. Follow the idea of MacOSX UI: the button contains a simple, easy phrase that is meaningful by itself. Exampleç you change a file extension and a dialog pops up saying:
"Are you sure you want to change the extension from .py to .ps?"
If you perform the change, the document could be opened by a different application.
(Use .ps) (Keep .py)
It is way more communicative than OK/Cancel, and your question becomes almost superfluous, that is, you just need to keep active the rightmost button, which seems to be the standard.
As it concerns the raw question you posed. Never do it. Ever. Not even at gunpoint. Consistency is an important requisite for GUIs. If you are not consistent you will ruin the user experience, and your users will most likely to see this as a bug than a feature (indeed it would be a BUG). Consistency is very important. To break it, you must have very good reason, and there must not be another different, standard way to achieve the same effect.
I wonder if you're thinking about the option that exists in Visual Basic where you can set various prompts and response options; and one option is to allow you to switch Cancel and OK based on which should be the default; so the user could just hit enter and most of the time get the proper action.
If you really want to head in this direction (which I think is a bad idea, and I'm sure you will too after little reflection and reading all the oher posts) it would work even better to include a capcha display for OK.
Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 10 months ago.
Improve this question
Have you ever been in a situation where a menu function you really really want to use but can't cause it's disabled or worse gone all together?
There is an argument for always leaving menus enabled and then display a message to a user explaining why a menu function can not be activated when they click on it. I think there is merit in this but maybe there is a cleverer way of addressing this issue.
I would be interested to hear what others think.
If you're refering to Joel's post Don't hide or disable menu items, he clarified in the StackOverflow podcast that he intended that there be information - not a dialog - telling you why a menu item wouldn't do anything:
So, the use-case I was thinking of was, you had mentioned that in the Windows Media Player, you can play things faster when you're listening to podcasts and so forth, and it'll speed them up. And when I looked in there, that was disabled. And I couldn't figure out how to enable it. And obviously the help file is no help--not that anybody reads help files, but even if you did you couldn't find the answer to that. And that was kind of frustrating, and I'd rather have that menu item be enabled and have it just tell me "I'm not going to do this right now because of the following reason. I refuse to do this."
As with most questions about usability, the answer is "it depends". It depends on the problem domain, the type of user, how critical the function is and so on. There is no single answer to your question.
I think the general consensus is, never ever totally remove items from a menu. Menus allow the user to freely discover what functions are available, but if those items are hidden or move around it does nothing to help the user. Also, moving them around makes it impossible to become proficient with the application since you have to constantly scan the menus for the item you want to select.
As for disabling versus enabling an item and displaying a dialog or message explaining why it's not something you can do, I generally prefer the former. However, if there's a function that a user can't reasonably be expected to intuit from the display, leaving it enabled is a good choice.
For example, if "Paste" is disabled it's reasonably obvious to most computer users that there's nothing to paste. However, if you have a "Frizzle the Bonfraz" menu item and the user may not know what a Bonfraz is or why they might want to enable it but can't, it's a good idea to leave it enabled at least for a while.
So again, it depends. If at all possible, do what you think is best and then ask your users.
To generalize it a bit (perhaps incorrectly...), which of these situations would you prefer:
To find yourself on an island with no boat or bridge in site. Of course, you could talk to the villager in town and he would tell you the magical word to make a bridge appear...but you had no idea that magic existed.
You see that there is a bridge; however, when you get to it, there is a sign telling you that the bridge is not open to use.
You see that there is a bridge and celebrate! When you get to the end of the bridge, it tells you that the exit is not open. They must go back.
Maybe I am biased, but I don't believe that leaving the menu options enabled and allowing the user to click on it is the best of idea. That's just wasting someone's time. There is no way for them to distinguish that the item is available or not until they click on the item. (Scenario #3)
Hiding the item all together has its pros and cons. Completely hidden and you run the risk of the user never discovering all these features; however, at the same time, you are presented with the opportunity of making your application 'fun' and 'discoverable.' I've always thought the visibility of actions is more suited to items like toolbars. A good example of that is in when in some applications the picture toolbar pops up when you click on an image...and disappears when you click on text. In general, I would say that something like this is best if the overall experience of your application lends towards a "discovering" and "exploring" attitude from the user. (Scenario #1)
I would generally recommend disabling the items and providing a tooltip to the user informing them how to enable it (or even a link to Help?); however, this cannot be overdone. This must be done in moderation. (Scenario #2)
In general, when it's a context-related action (i.e. picture toolbar) that the user can easily discover, hide the items. If the user won't easily find it, have it disabled.
Make it disabled but have the tooltip explain why it's disabled
It depends on the situation. If the menu item has applies in the current context but isn't available because of state, it should be disabled. If the context has changed so it no longer applies, it should be removed.
I've never really understood this myself (I don't program GUIs). Why even have menu items hidden or disabled in the first place? It is non-intuitive for most users who are looking for a particular menu option to find it disabled, or not even present.
Tooltips are also non-intuitive. If I'm moving my mouse across menu items, I'm not going to pause long enough to get a tooltip explanation. I'm more likely to become frustrated that something I expected to be accessible through the menu isn't there, or is disabled.
That said, I actually don't use GUI menus very often. I find the options available are often not useful, or are accessible in some more intuitive way, such as common keyboard shortcuts.
You can display the 'reason' in the status bar. Or even better, use a text that describes the action and contains information when such action is possible. For example, for 'Copy' menu item, the text in status bar would be: Copy the selected text. Note the 'selected' part, which tells the user that he needs to select the text to enable the menu item.
Another example in a tool I'm making, we have 'Drop database' menu item, but this action is only possible when you're connected to it. So, the text in status bar goes something like: 'Drop the database (only when connected)'.
I've always believed that you should hide as much as you can. (Your application shouldn't be any more complex than what the user can/should do.)
If you display a menu option that a user shouldn't be using, they may click on it, but think your application is broken because nothing happens.
That's what I think at least...