IE8 will crash if you try to set the width in percentage together with a background color in Fx.Morph.
I made an simple example on http://jsfiddle.net/SyBaa/
if you change the unit from "%" into "px" then it will not crash.
This is what my IE8 log was showing:
"Invalid property value. @ mootools-core-1.4.5-full-nocompat.js, line 3772 character 3"
It seems Fx.Morph add's the percentage unit to the background color.
Fix #2428 IE8: Fx.Morph percentage unit issue
Moving to the PR.
careful there, there's no pull request for this bug, that message above is just that this bug was referenced on a fork.
ah good, seems I even commented over there a while back. For some reason github didn´t add the reference here.
sorry for jumping the gun.