To get default minecraft textures, go in your .minecraft folder. Then, go to ".minecraft/versions/1.7.2".
Open your 1.7.2.jar file as a .zip file. Finally, when you're in the .jar, go to "assets\minecraft\textures\gui".
You can find a "widgets.png" file. This is what you're searching. To edit fonts, go to "assets\minecraft\textures\font".
The simple characters are in the "ascii.png" file. Sorry for my bad english, i'm french
I think no one understands what I mean, I directly translate the buttons in minecraft pocket edition in Spanish, I do not carry textures or anything like that, I've seen textures like Sphax that have custom buttons to play, play on realms, etc. ...
A mean those buttons, I do not want to carry a pack of textures, if not change minecraft texture to translate.