Apple Mac OS X keyboard viewer got stuck maximized

My mom likes pushing buttons, but today she pushed the wrong one. She often uses keyboard viewer to assist her with input methods because she couldn't remember the key mappings. Once the keyboard viewer windows is shown, you can click on the green button to maximize the keyboard viewer, and clicking on the green button again should restore its original size. However, if you drag the keyboard viewer in its maximized state just slightly off the screen, then the green button no longer restores the keyboard viewer back to its original size. The maximized keyboard viewer looks like this and occupies half of the screen.

This happens on Mac OS X Lion (10.7). Not sure if this happens with other versions also.

The solution is to first close the keyboard viewer, then use Terminal (under Applications/Utilities) and enter the following command at the prompt:

defaults delete com.apple.KeyboardViewer

The keyboard viewer should be restored to its original state next time you open it.

Another issue my mom was having was that when she tried to enter Chinese, certain characters cause programs to crash (also known as 地雷字, di lei zi, meaning “landmine characters”). It turns out the culprit is the "Use symbol and text substitution" option. It can be turned off under Preferences, Language & Text, Text. Text substitution erroneously matches some input sequences prematurely from the input method and causes invalid characters to be entered into the program.