While holding down the Ctrl + Alt keys, click on one of the elements in the menu. A turquoise box should appear round it.

Then, for specific element erase, press caps lock and draw on the screen. Only the element you selected will be erased. Or for specific element erase, press Insert and draw. Only the element you selected will be replaced.

This also works with menu sections, so for example you could erase all solids or all radioactive elements by Ctrl+Alt+clicking one of the icons on the right hand side of the window.

@MaravekZane (View Post)
All users are able to edit the wiki, so you could do that yourself ;-)

@boxmein (View Post)
Yes, it was shift+alt before. Might have been changed when line snapping was added.