Here is the technical explanation that should help you solve the problem nicely (without a horible white box
). To avoid drawing on top of other buttons, Messenger Plus! checks if the area is the following manner: for each line or pixel when the icon will be placed, every pixel must have the EXACT same RGB value. Each line can be a differentcolor but on any given line, every pixel must look a like.
In your theme, there's probably a little difference between somepixels, I'm sure you can change that quickly and photoshop, nobodywill see anydifference and the icon will be displayed
.
PS: sorry for the very late answer, I just saw this thread.