Don't increment read-only cells on a multiple-click.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.1@4795 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

test/sudoku.cxx

@@ -547,7 +547,7 @@ SudokuCell::handle(int event) {
       break;
 
     case FL_PUSH :
-      if (Fl::event_inside(this)) {
+      if (!readonly() && Fl::event_inside(this)) {
         if (Fl::event_clicks()) {
 	  // 2+ clicks increments/sets value
 	  if (value()) {