I'm using the PHP flavor of NetBeans.
Whenever I press Alt+Tab in Windows to switch to another application and then Alt+Tab back to NetBeans, the top menu is in focus..meaning I can press "F" to open the File menu and so on.
I can only imagine this is because the initial Alt keystroke I enter when pressing Alt+Tab is not getting reset when I return to the application.
This bug may seem minor, but it is a huge pain when you have to copy and paste text from another file into the editor. It forces you to press Alt (or Esc) upon returning to the app so the cursor in the editor appears again and you can paste your text.
I agree, this is very annoying, but unfortunately this is problem on swing side, we cannot do anything in Netbeans with it. See bug 73960
*** This bug has been marked as a duplicate of bug 73960 ***