@Override
	public void closeHover() {
		activeHoverService = null;
		lastField = null;

		DockingUtils.hideTipWindow();

		if (popupWindow != null) {
			popupWindow.dispose();
			popupWindow = null;
		}
	}
Sets the object that decides where to place the popup window. 
@param popupWindowPlacer the placer
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/hover/AbstractHoverProvider.java