I noticed this while using a combination of drag & drop and Effect.Highlight. I had set a hoverclass to set background color on my Droppables, and used Effect.Highlight in the onDrop callback. But then I noticed that after one drop, the hoverclass was no longer having any effect. I traced this to the line:
if(!this.options.restorecolor)
in Effect.Highlight which of course means that Effect.Highlight will never restore an empty value background color, so the background color was simply stuck at white after the first drop. My change should allow a user to specify something like
restorecolor: ""
while still falling back to the default if no restorecolor is given at all.
I realize that a workaround would be to use the Droppables onHover callback to set the background color directly, but it seems more reasonable to allow Effect.Highlight to set the background color to be empty.
I checked on Firefox 1.5, IE 6, and Safari 2.0 to make sure this does what I think it does.