protected void buttonDeleteActionPerformed(ActionEvent evt) {
		for(JTextComponent uiSource: uiSources) {
			if(uiSource.isFocusOwner()) {
				String text = uiSource.getText().trim();
				if(text.length() != 0) {
					uiSource.setText(text.substring(0, text.length() - 1));
					if(uiSource instanceof JFormattedTextField) {
						try {
							((JFormattedTextField) uiSource).commitEdit();
							((JFormattedTextField) uiSource).setValue(((JFormattedTextField) uiSource).getValue());
						} catch (ParseException e) {
							((JFormattedTextField) uiSource).setValue(0);
						}
					}
				}
				break;
			}
		}
	}