-
the default value (`-1`) did not correspond to any choice list entry, thus causing buggy behaviour wrt. saving preferences. (which is very noticeable in a new preferences interface i have built). this adds the `-1` choice list entry for 'absolute' to fix that. --- i questioned whether adding such an entry was correct in terms of it possibly being redundant alongside top-left + offsets. i noted that there is a specific code path for absolute mode involving marking the spu as positioned absolutely. i am not certain whether or not this is actually redundant for these plugins, and thus did not implement the alternative solution of ripping out those absolute mode bits and changing the default to `5` (top-left). my understanding, from spending time researching git history and the current codebase (without a great understanding of the spu code yet though) is that the absolute property comes into play when there are multiple spus, being to do with prevention of overlaps. absolute mode forces position, whilst non-absolute allows moving spus to fix overlap.
16a61233
