I upgraded to Mac OS X Lion last month and there has been quite a few changes to get used to. One thing I noticed was that my clear key on the full keyboard doesn’t work anymore in the Calculator widget. After a little searching, I found a solution!

1. Open up a finder window and navigate to the following folder:

/Library/Widgets

2. Next locate Calculator.wdgt and ctrl-click on it, then select “Show Package Contents.”
3. Copy Calculator.js to some other location such as your desktop.
4. Open the file up in any text editor.
5. Goto line 127, and change “case 63289″ to “case 61705″. It should look like this when you are done.

case 61705:
case 27:
	key = "c";
	break;

6. Close and save the file.
7. Copy the file back to the contents of Calculator.wdgt.
8. Fire up dashboard and remove your current calculator widget and add a new one.

You’re clear button will now work in Calculator!

Here is the link to the original solution.