editor template mouseover background css

[squishi]

On the editor page, the css property background gets set to a color that I believe is the "body" color on the "Main CSS" page.
This happens when I mouseover a button with the CSS property imagebutton.

I want to know where this mouseover property is set. I want to remove it so that my editor buttons no longer disappear on mouseover.

So again: vbulletin resets the background property of the imagebutton class elements on mouseover.
Where can I find this mouseover functionality?

--------------- Added [DATE]1285089372[/DATE] at [TIME]1285089372[/TIME] ---------------

This is what gets added to the imagebutton element's style on mouseover:

element.style {
background:none repeat scroll 0 0 #E1E1E2;
border:1px solid #316AC5;
color:#000000;
padding:1px;
}

On mouseout, the border gets changed a little, the style is not removed.
Therefore the background-image property that I have set for the imagebutton elements gets overwritten.

Where can I find this code?