Need to perform multiple clicks in MacBook Pro 2011 running OS X Lion I have noticed that I need to perform clicks multiple times if I want to close some window e.g. Firefox or even to close a tab. It happens frequently but not all the time. When I use the Eclipse IDE, if I select attributes options from property explorer, a few button/drop-downs are click-able, whereas for others I click on the buttons but there's no response.

Is this a bug in OS X Lion?

Example of clicking on Eclipse IDE fails to respond, even I have pressed the dropdown button.
This is not a known but to my knowledge. Have you tried running a test OS from an external volume that has a fresh install of Lion (with all updates) to see if the issue still remains? Is your system able to run 10.6.8? If so try a known good volume with Snow Leopard and test again.
It might be of use to try those OSs out to help narrow it down. Best of luck.