number of columns in it, it turns out that getting column information from
the associated control is much easier than copying it into the control.
- Provide wxHeaderCtrlSimple derived class which can be used easily if
callback approach of wxHeaderCtrl is not needed.
- Because of wxHeaderCtrl virtualization, port-specific implementations of
wxHeaderColumn are not needed any more and were removed.
- Use wxHeaderCtrl in the generic wxDataViewCtrl: this means that column
events are broken right now in it as they haven't been implemented by
wxHeaderCtrl yet, this will be fixed a.s.a.p.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57161 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
