private URL createTempUrl() {
		if (tempFileFailed) {
			return null; // don't repeatedly attempt to create a temp file
		}

		try {
			File imageFile = Application.createTempFile("temp.help.icon", null);
			imageFile.deleteOnExit(); // don't let this linger
			ImageIcon imageIcon = ResourceManager.getImageIcon(icon);
			ImageUtils.writeFile(imageIcon.getImage(), imageFile);
			return imageFile.toURI().toURL();
		}
		catch (IOException e) {
			tempFileFailed = true;
			Msg.error(this, "Unable to write temp image to display in help for " +
				ResourceManager.getIconName(icon));
		}
		return null;
	}
Returns the value of {@link #getUrl()} if it is non-null.  Otherwise, this class will
attempt to create a temporary file containing the image of this class in order to return
a URL for that temp file.  If a temporary file could not be created, then the URL 
returned from this class will point to the 
{@link ResourceManager#getDefaultIcon() default icon}.

@return the URL
Ghidra/Framework/Gui/src/main/java/resources/IconProvider.java