Black background on menu buttons

I'm a new user of True Launch Bar and one of the reasons I wanted it was its compatibility with Windows 7's glass look. The problem is that when my mouse is on a menu button, the background on the button turns black. It doesn't happen to normal (non-menu) buttons.

(In the pictures the printscreen removed the mouse arrow but I'm sure you can tell which button the mouse was on when the printscreen was done)

Thanks.