static boolean isIconOnlyOrSingleCharacterButton( Component c ) {
		if( !(c instanceof JButton) && !(c instanceof JToggleButton) )
			return false;

		Icon icon = ((AbstractButton)c).getIcon();
		String text = ((AbstractButton)c).getText();
		return (icon != null && (text == null || text.isEmpty())) ||
			(icon == null && text != null &&
			 ("...".equals( text ) ||
			  text.length() == 1 ||
			  (text.length() == 2 && Character.isSurrogatePair( text.charAt( 0 ), text.charAt( 1 ) ))));
	}
Returns true if the button has an icon but no text,
or it does not have an icon and the text is either "..." or one character.
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java