Menu seperator expand/colapse - Great! But how do you skin it?

I just found the expand/collapse setting for the menu seperators. What a great feature! However, I'm curious about how to change the skin of the little +/- button. It seems to be trying to use my standard button bitmap, but for some reason it has a blue border? My button bitmap is basically greyscale (with some MagicPink™ for tranparency) with no hint of blue in it at all.
Looking closer at it, it might not be the same bitmap after all. Is it skinnable?

Oh, sorry. System info:

Win2k Pro w/ SP3
TLB 1.2.7 RC3
IE 6
GeForce2 MX400 @ 1152x864 32bit

Should just make a text file of my system info so I can cut and paste

Sorry I miss this in docs Here how to skin separator images:

[Separator Images]
bitmap=<bmp filename>
Transparent=<True or False>
TransparentColor=0x<BBGGRR>

Bitmap with images must to be like this:

Great! Thanks!

Now.. is there any way to have it collapse/expand what's above it instead of what's below it?

Default gui behaviour in windows is to always expand below.

I understand that, but I was wondering if the software could be altered to offer a choice in a future release. I have my taskbar on the bottom (as I'm sure a lot of folks do), and I use the expand/collapse feature to hide less frequently used items. This puts the seperator on the bottom when those items are collapsed. I would just like to have the seperator at the top, so the more ferquently used items stay at the bottom (and thus, closer to the mouse). While I'm back on the subject, it'd also be kinda nice to have the seperators auto expand after the mouse hovers inside the menu for a user definable amount of time, i.e. Win2k/XP personalized menus. And I'd love to see seperate skin settings for the items inside the collapsable area. But maybe I'm getting ahead of myself now