Add the possibility to disable invisible wxDataViewCtrl items.

Add new wxDataViewModel::IsEnabled() and wxDataViewListStore::IsEnabledByRow()
methods and implement support for actually disabling the items in wxOSX/Cocoa
native implementation of wxDataViewCtrl and limited support for it in the
generic version.

We need to implement this in wxGTK using GtkCellRenderer "sensitive" propriety
later.

Closes #12686.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66403 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/cocoa/dataview.mm

@@ -1695,6 +1695,9 @@ outlineView:(NSOutlineView*)outlineView
     model->GetAttr(dvItem, colIdx, attr);
     renderer->OSXApplyAttr(attr);
 
+    // set the state (enabled/disabled) of the item
+    renderer->OSXApplyEnabled(model->IsEnabled(dvItem, colIdx));
+
     // and finally do draw it
     renderer->MacRender();
 }
@@ -2487,6 +2490,11 @@ void wxDataViewRenderer::OSXApplyAttr(const wxDataViewItemAttr& attr)
         [(id)cell setTextColor:colText];
 }
 
+void wxDataViewRenderer::OSXApplyEnabled(bool enabled)
+{
+    [GetNativeData()->GetItemCell() setEnabled:enabled];
+}
+
 IMPLEMENT_ABSTRACT_CLASS(wxDataViewRenderer,wxDataViewRendererBase)
 
 // ---------------------------------------------------------