Yes, it is possible that update of new version can replace this file for a new one and this hack would be lost. Unfortunatelly I still haven’t found better solution that works.
I got rid of tooltip by replacing attribute title for data-title at tag. Using data-title attribute makes description in the lightbox stil visible.
My solution:
in ..\wp-content\plugins\final-tiles-grid-gallery-lite\lib\gallery-class.php
replaced code snippet
$title = ( in_array( $gallery->lightbox, array(
'prettyphoto',
'fancybox',
'swipebox',
'lightbox2'
) ) ? "title" : "data-title" );
for
$title = ( in_array( $gallery->lightbox, array(
'prettyphoto',
'fancybox',
'swipebox',
'lightbox2'
) ) ? "data-title" : "data-title" );
