Taking wordpress 3.0.2 as an example, open wp-includes/js/thickbox/thickbox.js and find the following line of code:
About line 135, below // End Resizing, modify the id='TB_ImageOff' to id='TB_nextImage',
Then if (!(TB_NextHTML === "" not far below the line )){} add:
jQuery("#TB_nextImage ").click(goNext);
Place jQuery("#TB_next").click(goNext); on the next line.
Update:
Suddenly discovered I forgot to change the title of the link. The above code allows you to click on the picture to directly view the next picture. However, the title of the picture link (the yellow block when the mouse is placed on it) has not changed. This is very simple. Change
title ='" thickboxL10n.close "' can be changed to title='" thickboxL10n.next "'. This will read the language pack to display the prompt, or you can write it directly as a string. The effect is as follows: