There's missing the ability to add the spin control for floating-point values: wxSpinCtrlDouble. There's only one for integers.
Actually it's: wx.lib.agw.floatspin.FloatSpin
As far as I can tell, wx.lib.agw.floatspin.FloatSpin is a wxPython widget.
In wxWidgets 2.9.0 a wxSpinCtrlDouble widget was added which is like wxSpinCtrl but for floating point numbers (in C++, the value is of type double).
The attached patch adds support to the 'additional' widgets plugin for wxSpinCtrlDouble. It was generated against a clean version of r2203.