Fix several rounding problems with float values in wxPropertyGrid.

See also r85980 in the trunk.

Closes #15625.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@77960 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/propgrid/props.h

@@ -316,6 +316,7 @@ public:
                                 const wxString& text,
                                 int argFlags = 0 ) const;
     virtual bool DoSetAttribute( const wxString& name, wxVariant& value );
+    virtual wxVariant DoGetAttribute( const wxString& name ) const;
     virtual bool ValidateValue( wxVariant& value,
                                 wxPGValidationInfo& validationInfo ) const;