INT 2F - European MSDOS 4.0 POPUP - "SavePu" - SAVE POPUP SCREEN
        AX = 1402h
        ES:DI -> save buffer (0000h:0000h for default buffer in POPUP)
Return: CF clear if successful
        CF set on error
            AX = error code
                0001h process does not own screen
                0004h unknown error
                0005h invalid pointer
SeeAlso: AX=1401h"POPUP",AX=1403h"POPUP"