KAG Emoticon confusion

In game emoticons have white speech bubbles around them, however the file for emoticons themselves have no such bubbles, at first i thought that the code of the game must cut the bubble out, how ever after removing the transparency from the sheet all the emoticons had white boxes around them meaning that the code dose not pick them out. Confused i went back to the original file and re examined it and there were no bubbles of different color. I am confused how dose the game pick out these bubbles?

 

Ohhhh shit, i just realized that there probably is or rather was a white bubble around said emoticon when they made the sprites in whatever program they use and then when they transferred to the game the code recognizes it but the default program paint dose not and because its been turned into a file any other programs probably would not recognize the bubbles either, is this the case?