Javafx : Activate a tooltip with a button

This is what you are looking for:

final Button helpButton = new Button("Help");
helpButton.setOnAction(new EventHandler()
{
    public void handle(Event arg0)
    {
        showTooltip(stage, helpButton, "test tool tip", null);
    }
});

public static void showTooltip(Stage owner, Control control, String tooltipText,
    ImageView tooltipGraphic)
{
    Point2D p = control.localToScene(0.0, 0.0);

    final Tooltip customTooltip = new Tooltip();
    customTooltip.setText(tooltipText);

    control.setTooltip(customTooltip);
    customTooltip.setAutoHide(true);

    customTooltip.show(owner, p.getX()
        + control.getScene().getX() + control.getScene().getWindow().getX(), p.getY()
        + control.getScene().getY() + control.getScene().getWindow().getY());

}

Just pass the button as an input instead of control.

The ability to display a Tooltip on demand requires a resolution of RT-19538 Customizable visibility timing for Tooltip, which is not implemented in JavaFX 2.2.

As a workaround, you could try any of the possible strategies below:

1. Displaying your Tooltip data in a ContextMenu instead. With a ContextMenu, you have complete control over when it is shown.
2. You could create a custom PopupControl for your required functionality.
3. You could replace the default TooltipSkin with a custom implemented skin which allows you to control when the Tooltip is displayed.
4. You could implement RT-19538 and provide a patch to the Tooltip and TooltipSkin to the openjfx project.

3rd party libraries such as Jide's JavaFX Beta Release provide special classes like Decorator utilities, IntelliHints and ShapedPopups which might be useful in your case.