GZDoomBuilder 1.06a:

MODELDEFs and models can now be loaded from PK3 resources (does anybody know if models or MODELDEFs can be stored in WADs?).
Negative scale and zOffset are now correctly parsed from MODELDEFs (model surfaces may be inverted though).
Fixed a crash while reading MODELDEFs when Operation System's decimal separator was set to comma.
Fixed a crash when user changed Thing type in Visual mode to a new one with model override, which wasn't previously used in a map.
Fixed a bug introduced in 1.06 when models weren't rendered in Visual mode when Fullbright mode was on.
Non-breaking space is now correctly handled by all Doom Builder's data parsers.
ColorPicker plugin:
Fixed a crash when user attempted to open ColorPicker window to edit sector properties in Visual mode, using hilighted surface as selection source, without selecting anything before doing so.