* numeric conventions - it will also allow formulas (a formula is when the
* first value is a "=" which means it is meant to be taken as the user
* typed)
*/
public static KeyPressHandler getNumericFilter(final TextBox box) {
return new KeyPressHandler() {
public void onKeyPress(KeyPressEvent event) {
TextBox w = (TextBox) event.getSource();
char c = event.getCharCode();
if ( Character.isLetter( c ) && c != '=' && !(box.getText().startsWith( "=" )) ) {