Checks if an attribute (or any attribute) of a sample, stream, or MOD music is sliding.
|handle||The channel handle... a HCHANNEL, HSTREAM or HMUSIC.|
|attrib||The attribute to check for sliding... one of the following, or 0 for any attribute.|
other attributes may be supported by add-ons, see the documentation.
If the attribute is sliding, then TRUE is returned, else FALSE is returned.