Remove duplication in wxImageList defines and always default to using the native wxImageList when available, even for wxGenericListCtrl.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41271 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/imaglist.h

@@ -12,12 +12,39 @@
 #ifndef _WX_IMAGLIST_H_BASE_
 #define _WX_IMAGLIST_H_BASE_
 
+/*
+ * wxImageList is used for wxListCtrl, wxTreeCtrl. These controls refer to
+ * images for their items by an index into an image list.
+ * A wxImageList is capable of creating images with optional masks from
+ * a variety of sources - a single bitmap plus a colour to indicate the mask,
+ * two bitmaps, or an icon.
+ *
+ * Image lists can also create and draw images used for drag and drop functionality.
+ * This is not yet implemented in wxImageList. We need to discuss a generic API
+ * for doing drag and drop and see whether it ties in with the Win95 view of it.
+ * See below for candidate functions and an explanation of how they might be
+ * used.
+ */
+
+// Flag values for Set/GetImageList
+enum {
+    wxIMAGE_LIST_NORMAL, // Normal icons
+    wxIMAGE_LIST_SMALL,  // Small icons
+    wxIMAGE_LIST_STATE   // State icons: unimplemented (see WIN32 documentation)
+};
+
+// Flags for Draw
+#define wxIMAGELIST_DRAW_NORMAL         0x0001
+#define wxIMAGELIST_DRAW_TRANSPARENT    0x0002
+#define wxIMAGELIST_DRAW_SELECTED       0x0004
+#define wxIMAGELIST_DRAW_FOCUSED        0x0008
+
+#include "wx/generic/imaglist.h"
+
 #if defined(__WIN32__) && !defined(__WXUNIVERSAL__)
     #include "wx/msw/imaglist.h"
 #elif defined(__WXMAC_CARBON__)
     #include "wx/mac/imaglist.h"
-#else
-    #include "wx/generic/imaglist.h"
 #endif
 
 #endif