This is my problem
i try to change the buttons of explorer, but i encounter a problem:
after modifications of my images in browseui file and restart, the black line between the buttons is present: 
in other case, i get that:

the lign cuts my button
i know i must create an alpha layer in channel tab, but how must I fill it, what image must i change etc?
If someone succeed to correct this problem....sorry for my english