如果您只是想要一个工具提示通过节点（在您的情况下为按钮），使用 工具提示 及其 graphicProperty 而不是显示不同的 Stage 。

If you just simply want to have a tooltip over a Node (a Button in your case), it is reasonable to use a Tooltip and its graphicProperty rather than showing a different Stage.

// Load the image with the needed size
Image image = new Image("...", 150, 150, true, true);

// Place it over a Button
Button button = new Button();

Tooltip tooltip = new Tooltip();
tooltip.setGraphic(new ImageView(image));

button.setTooltip(tooltip);