// create buttons
ToggleButton lToggleButton = new ToggleButton("" + i);
lToggleButton.setId("day" + i);
lToggleButton.getStyleClass().add("day-button");
lToggleButton.selectedProperty().addListener(toggleButtonSelectedPropertyChangeListener); // for minimal memory usage, use a single listener
lToggleButton.onMouseReleasedProperty().set(toggleButtonMouseReleasedPropertyEventHandler); // for minimal memory usage, use a single listener
lToggleButton.onKeyReleasedProperty().set(toggleButtonKeyReleasedPropertyEventHandler); // for minimal memory usage, use a single listener
// remember which button belongs to this property
booleanPropertyToDayToggleButtonMap.put(lToggleButton.selectedProperty(), lToggleButton);