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