* in preferences viewers, a 0 value for samples should be detected and
  flagged as invalid
* when using BLT library in local directory, Preferences do not work
  since more of BLT (bindings) is needed, which requires a proper
  package installation
* fix empty element label problem in viewer when loading from a
  asynchronous module save file: update labels at each poll?
* pies shows doubled / slanted 0 line sometimes when resizing
* in dnd stacked drops sites show highlighting residue when cursor is
  hovering over

