I believe that 'pop-up' is the DOS box they're referring to. It should close by itself, when it does the conversion is done. At least that's how it works for me.
You can tell if it worked by comparing the before and after file size, a 1024x1024 32 bit bitmap is usually 4.00 mg and the dxt3 version is usually 1.00 mg, assuming no mipmaps are included.
I have the JF P-38 pack and this helped me to cure the texture blurries. The vc still loads kinda slow, but it does load and is readable.
You can tell if it worked by comparing the before and after file size, a 1024x1024 32 bit bitmap is usually 4.00 mg and the dxt3 version is usually 1.00 mg, assuming no mipmaps are included.
I have the JF P-38 pack and this helped me to cure the texture blurries. The vc still loads kinda slow, but it does load and is readable.