acceptWidgets better doc

* fixed doc and updated two.html with actual example
* fix for #1113

Author: Alain Dumesny

demo/two.html

@@ -103,7 +103,7 @@ <h1>Two grids demo</h1>
         float: false,
         removable: '.trash',
         removeTimeout: 100,
-        acceptWidgets: '.grid-stack-item'
+        acceptWidgets: function(i, el) { return true; } // function example, else can be simple: true | false | '.someClass' value
       };
       $('#grid1').gridstack(options);
       $('#grid2').gridstack($.extend({}, options, {

doc/README.md

@@ -62,8 +62,10 @@ gridstack.js API
 
 ## Options
 
-- `acceptWidgets` - if `true` of jquery selector the grid will accept widgets dragged from other grids or from
- outside (default: `false`) See [example](http://gridstackjs.com/demo/two.html)
+- `acceptWidgets` - accept widgets dragged from other grids or from outside (default: `false`). Can be:
+   * `true` (uses `'.grid-stack-item'` class filter) or `false`
+   * string for explicit class name
+   * function (i: number, element: Element) returning a boolean. See [example](http://gridstack.github.io/gridstack.js/demo/two.html)
 - `alwaysShowResizeHandle` - if `true` the resizing handles are shown even if the user is not hovering over the widget
   (default: `false`)
 - `animate` - turns animation on (default: `false`)

src/gridstack.d.ts

@@ -398,10 +398,12 @@ declare namespace GridStackUI {
  */
 interface GridstackOptions {
   /**
-   * if true of jquery selector the grid will accept widgets dragged from other grids or from
-   * outside (default: false) See [example](http://gridstack.github.io/gridstack.js/demo/two.html)
+   * accept widgets dragged from other grids or from outside (default: `false`). Can be:
+   * `true` (uses `'.grid-stack-item'` class filter) or `false`,
+   * string for explicit class name,
+   * function returning a boolean. See [example](http://gridstack.github.io/gridstack.js/demo/two.html)
    */
-  acceptWidgets ? : boolean | string | ((i: number, element: Element) => boolean | string);
+  acceptWidgets ? : boolean | string | ((i: number, element: Element) => boolean);
 
   /**
    * if true the resizing handles are shown even if the user is not hovering over the widget (default?: false)