## Class hierarchy

The class hierarchy has changed somewhat. wxToolBar and wxButtonBar classes have been split into several classes, and are derived from wxControl (which was called wxItem). wxPanel derives from wxWindow instead of from wxCanvas, which has disappeared in favour of wxScrolledWindow (since all windows are now effectively canvases which can be drawn into). The status bar has become a class in its own right, wxStatusBar.

There are new MDI classes so that wxFrame does not have to be overloaded with this functionality.

There are new device context classes, with wxPanelDC and wxCanvasDC disappearing. See Device contexts and painting.