backported wxSizer::SetSizeHints() fix to make it work correctly when the best size decreases

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@52332 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -122,6 +122,7 @@ All (GUI):
   wxRESERVE_SPACE_EVEN_IF_HIDDEN sizer flag.
 - Added wxWindow::ClientToWindowSize() and WindowToClientSize() helpers.
 - Added wxSizer::ComputeFittingClientSize() and ComputeFittingWindowSize().
+- Fixed wxSizer::SetSizeHints() to work when the best size decreases.
 
 All (Unix):
 

src/common/sizer.cpp

@@ -885,12 +885,19 @@ void wxSizer::SetSizeHints( wxWindow *window )
     // Preserve the window's max size hints, but set the
     // lower bound according to the sizer calculations.
 
-    wxSize size = Fit( window );
+    // This is equivalent to calling Fit(), except that we need to set
+    // the size hints _in between_ the two steps performed by Fit
+    // (1. ComputeFittingWindowSize, 2. SetSize). That's because
+    // otherwise SetSize() could have no effect if there already are
+    // size hints in effect that forbid requested size.
+    const wxSize size = ComputeFittingWindowSize(window);
 
     window->SetSizeHints( size.x,
                           size.y,
                           window->GetMaxWidth(),
                           window->GetMaxHeight() );
+
+    window->SetSize(size);
 }
 
 void wxSizer::SetVirtualSizeHints( wxWindow *window )