private static float getRoundedBorderWidth( Component owner, Component contents ) {
		String uiKey =
			(contents instanceof BasicComboPopup) ? "ComboBox.roundedBorderWidth" :
			(contents instanceof JPopupMenu) ? "PopupMenu.roundedBorderWidth" :
			(contents instanceof JToolTip) ? "ToolTip.roundedBorderWidth" :
			"Popup.roundedBorderWidth";

		Object value = getOption( owner, contents, FlatClientProperties.POPUP_ROUNDED_BORDER_WIDTH, uiKey );
		return (value instanceof Number) ? ((Number)value).floatValue() : 0;
	}
Checks whether the owner component returns a tooltip location in
JComponent.getToolTipLocation(MouseEvent).
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java