Don't pop explicitly changed status messages.

Calls to SetStatusText() in between Push/PopStatusText() were simply lost
before, now the text explicitly changed by SetStatusText() is preserved by the
next call to PopStatusText().

This required adding a new virtual method, called DoUpdateStatusText(), which
is now implemented in all the derived classes instead of overriding
SetStatusText() (on the bright side, it doesn't need to do any checks already
done in the base class any more).

Also fix PushStatusText() to actually show the text being pushed at all under
wxMSW as a side effect.

And further reduce code duplication between wxStatusBarBase and the derived
classes.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61624 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/statusbr.h

@@ -44,20 +44,9 @@ public:
                 long style = wxSTB_DEFAULT_STYLE,
                 const wxString& name = wxStatusBarNameStr);
 
-    // Create status line
-    virtual void SetFieldsCount(int number = 1,
-                                const int *widths = (const int *) NULL);
-
-    // Set status line text
-    virtual void SetStatusText(const wxString& text, int number = 0);
-
-    // Set status line widths
+    // implement base class methods
     virtual void SetStatusWidths(int n, const int widths_field[]);
-
-    // Get the position and size of the field's internal bounding rectangle
     virtual bool GetFieldRect(int i, wxRect& rect) const;
-
-    // sets the minimal vertical size of the status bar
     virtual void SetMinHeight(int height);
 
     virtual int GetBorderX() const { return m_borderX; }
@@ -68,8 +57,10 @@ public:
 
     int GetFieldFromPoint(const wxPoint& point) const;
 
-protected:      // event handlers
+protected:
+    virtual void DoUpdateStatusText(int number);
 
+    // event handlers
     void OnPaint(wxPaintEvent& event);
     void OnSize(wxSizeEvent& event);