Custom Tooltip blp (request)

[Berb]

I've been playing around with the UI-Tooltip-Border.blp and UI-Tooltip-Background.blp for a while now trying to make then both black to match the tooltip addon I currently use (aTooltip from ALZA UI). I'm almost there (example screenshot here), but I want the right one (work in progress) to look the same as the left one (tooltip addon). They're close, but that solid black line is kind of annoying.

Another, and probably easier, way I could to do this is add the tooltip names (GameTooltip, ItemRefTooltip, ShoppingTooltip1) to the list in the aTooltip addon, but I currently have no idea how to retrieve these tooltip names.