Backported from wx2.9: Greatly reduce rare animation garbage in wxOwnerDrawnComboBox drop-down animation (see #12087)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@64477 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -102,6 +102,8 @@ wxMSW:
   have more native-like focus indicator rendering.
 - Fixed wxOwnerDrawnComboBox keyboard handling: drop-down is no longer
   displayed when arrow key is pressed (without Alt).
+- In some rare cases wxOwnerDrawnComboBox drop-down animation could display
+  as garbage. This has now been greatly reduced (mcben).
 
 2.8.11:
 -------

src/msw/combo.cpp

@@ -799,6 +799,7 @@ void wxComboCtrl::OnTimerEvent( wxTimerEvent& WXUNUSED(event) )
 {
     bool stopTimer = false;
 
+    wxWindow* win = GetPopupWindow();
     wxWindow* popup = GetPopupControl()->GetControl();
 
     // Popup was hidden before it was fully shown?
@@ -810,7 +811,6 @@ void wxComboCtrl::OnTimerEvent( wxTimerEvent& WXUNUSED(event) )
     {
         wxLongLong t = ::wxGetLocalTimeMillis();
         const wxRect& rect = m_animRect;
-        wxWindow* win = GetPopupWindow();
 
         int pos = (int) (t-m_animStart).GetLo();
         if ( pos < COMBOBOX_ANIMATION_DURATION )
@@ -828,8 +828,10 @@ void wxComboCtrl::OnTimerEvent( wxTimerEvent& WXUNUSED(event) )
             }
             else
             {
-                popup->Move( 0, -y );
+                // Note that apparently Move() should be called after
+                // SetSize() to reduce (or even eliminate) animation garbage
                 win->SetSize( rect.x, rect.y, rect.width, h );
+                popup->Move( 0, -y );
             }
         }
         else
@@ -840,9 +842,13 @@ void wxComboCtrl::OnTimerEvent( wxTimerEvent& WXUNUSED(event) )
 
     if ( stopTimer )
     {
-        popup->Move( 0, 0 );
         m_animTimer.Stop();
         DoShowPopup( m_animRect, m_animFlags );
+        popup->Move( 0, 0 );
+
+        // Do a one final refresh to clean up the rare cases of animation
+        // garbage
+        win->Refresh();
     }
 }
 #endif