In my application if the user tries to press CTRL + V to paste something with nothing really in the clipboard .I wish to inform the user about the same meaning a informative message saying that Clipboard empty.I dont want to display nasty and ugly dialog box,instead something sort of a feedback tip which will just display and then fade off.But apart from that,is there anyother idea?
I think that the best way to show non important errors is using a toast. Toast are non intrusive with user actions, shows a small message and fades in a short time.
Firstly, consider if feedback is genuinely necessary. The pattern of paste action > nothing happens is so common across so many systems that people are used to it.
However, if you really need to provide feedback, use your suggested solution. Modal dialogs are inappropriate here as they interrupt the workflow for something that is not critical and doesn't prevent the user continuing. Your idea of a feedback tip is good. Take a look at SE's own tooltips and go with something similar. When the feedback is about an 'action the user has performed', use a neutral or success color such as yellow or green (again, SE has a good yellowy-beige for this). When the feedback is an error, such as in this case, use a red background. You may also want to scroll the page to the message, but be careful of this. Scrolling for non-essential messages again disrupts user workflow, so for something like this I recommend popping the message then leaving it.
As for positioning, again take a lead from SE. Position the message above the input field with a small arrow pointing down to the field. That way it's mear the location of the error so is easy for the user to see but doesn't obscure the user's viewport.
The fact that nothing happens when a user hits CTRL+V with an empty clipboard or invalid data is the feedback.
Adding a message won't provide the user with any additional information that they can act on and thus is unnecessary.
I would simply trigger the systems default "beep" sound. In Java it is triggered like this, if you want to know what I mean:
Apart from that the user surely will notice that nothing actually was pasted, the system warning sound could be helpful. Please don't use the error sound, since this isn't a system error - but a warning sound would enforce the feedback to the user, along with your fading message of an empty clipboard.
I'd start by considering what is the normal interaction here. 'Normal' isn't always 'best' but it's a good place to start especially for a feature that is ubiquitous across nearly all software and all operating systems.
In most cases, pasting empty content does nothing else in terms of alerting the user. I'd stick with that barring any other arguments as to why your app would need to behave differently.