#84 Values of hidden sub-properties visible in parent

[AmiArt]

The values of hidden sub-properties (which have wxPG_PROP_HIDDEN flag set) are still displayed in parents. This is true for both composed and aggregate parent properties (like wxFontProperty).

To reproduce this bug:
1. Start wxPropertyGrid sample app
2. Go to third page called 'Examples'
3. Select 'Car.Speeds.Max Speed (mph)' sub-property
4. Choose 'Hide' from 'Basic' menu - the selected property disappeared but it's value is still visible in 'Car' and 'Car.Speeds' parents (and can be modified)

Config:
wxWidgets 2.8.9, wxPropertyGrid 1.4.0, VC++ 2008