code for this is ugly (i.e., repetitive) and can probably be easily abstracted/refactored...

add a flag to drawsymbol/number visfn to allow updating existing objects instead of having to erase/redraw them

Make it possible to just send new attributes to GUI for [drawpolygon] and friends when a field value changes
(This performs better than erasing and redrawing the scalar in the GUI)

add note in todo about potential loss of data when > 4096 bytes of data
are entered into a message box and sent to Pd

change fielddesc_getfloat to fielddesc_getcoord so that the (admittedly arcane) scaling/quanta syntax can be used with [draw] methods where it makes sense

do a proper loadbang for canvas fields (needs more testing)

(differs slightly from mine in that the '-' character is used to mean
 a wildcard template)