So, I was looking through the BBCode options here, when I noticed the MouseImage code. Intrigue, I decided to test out the [MO=Option]Value[/MO] tag to see how it worked, given the sample there was not very helpful. As I soon discovered, provided you use an img url in place of option, the result will display that image, however the selection for value seemed to be ignored.

Looking at the page's html, I discovered the problem. If add the following to a post:
[MO=http://harem-battle.club/images/vNulletin/statusicon/forum_old-48.png]http://harem-battle.club/images/vNulletin/statusicon/forum_new-48.png[/MO]
I get:

This has the html code:
Code:
<img onmouseover="Javascript<b></b>: this.firstsrc= 
this.getAttribute('src'); this.secondsrc=
'http://harem-battle.club/images/vNulletin/statusicon/forum_new-48.png'; this.setAttribute('src',this.
secondsrc);" alt="" onmouseout="Javascript<b></b>: this.setAttribute
('src',this.firstsrc);" src="http://harem-battle.club/images/vNulletin/statusicon/forum_old-48.png">
The problem here is the "Javascript<b></b>: " in the onmouseover and onmouseout attributes. If this is removed, the code works as intended, though I suspect it would be more intuitive to reverse which image is the default and which is the one seen when moused over.

If this could be fixed, it would be appreciated.