There seems to be a problem with toggling subscript and superscript in the Editor control.
The following steps demonstrate it:
1) Go
here .
2) Select the Full radio button
3) Type a word in the editor window, select it with the mouse and then click e.g. the Bold icon - the word turns bold.
4) Click the Bold icon again - the word reverts to normal type, as expected.
5) Click the superscript button - the word is shown as superscript.
6) Click the superscript button - the word does not revert to normal type.
The above behaviour is 100% reproducible, and the subscript button also exhibits it.