Add wxBitmap ctor from wxCursor to wxGTK and wxMSW.

Allow converting wxCursor to wxBitmap in order to draw it, for example.

Closes #15699.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77537 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/bitmap.cpp

@@ -515,6 +515,19 @@ wxBitmap::wxBitmap(GdkPixmap* pixmap)
 }
 #endif
 
+wxBitmap::wxBitmap(const wxCursor& cursor)
+{
+#if GTK_CHECK_VERSION(2,8,0)
+    if (gtk_check_version(2,8,0) == NULL)
+    {
+        GdkPixbuf *pixbuf = gdk_cursor_get_image(cursor.GetCursor());
+        *this = wxBitmap(pixbuf);
+    }
+#else
+    wxUnusedVar(cursor);
+#endif
+}
+
 wxBitmap::~wxBitmap()
 {
 }