fix(Dropdown): Fix onClick for child elements not getting invoked (#208)

* Override toggle dropdown click inside

* Fixes for review and updating the demo

* Fixing issues with onClick of dropdown children not getting invoked

* Fix wording on demo for dropdown

src/components/Dropdown/Dropdown.md

@@ -38,7 +38,7 @@ By default the dropdown menu will not close when an item within the dropdown is
 
 ```jsx
 <Dropdown label="Toggle On Click" toggleDropdownOnClickInside>
-    <Button variant="plain">Item one</Button>
-    <Button variant="plain">Item two</Button>
+    <Button onClick={() => alert('Clicked Item one')}>Item one</Button>
+    <Button onClick={() => alert('Clicked Item two')}>Item two</Button>
 </Dropdown>
 ```

src/components/Dropdown/Dropdown.tsx

@@ -103,7 +103,8 @@ export class Dropdown extends React.PureComponent<DropdownProps & React.HTMLAttr
             return false;
         }
 
-        if (event.targets(ReactDOM.findDOMNode(this)) && !this.props.toggleDropdownOnClickInside && (!event.isKeyEvent() || event.isTabKeyPress())) {
+        const preventToggleOnInsideClick = !event.isKeyEvent() && !this.props.toggleDropdownOnClickInside;
+        if (event.targets(ReactDOM.findDOMNode(this)) && (preventToggleOnInsideClick || event.isTabKeyPress())) {
             // If the user clicks, touches or tabs inside the dropdown do not close the menu
             return false;
         }

src/components/Dropdown/DropdownEvent.ts

@@ -7,7 +7,27 @@ import AbstractUserActionEvent from '../util/AbstractUserActionEvent';
 export default class DropdownEvent extends AbstractUserActionEvent  {
 
     public static handler = (callback) => {
-        return AbstractUserActionEvent.handler(callback, DropdownEvent);
+        const eventHandler = (event) => {
+            callback(new DropdownEvent(event));
+        };
+        return ({
+            register: () => {
+                ['click'].forEach(event =>
+                    document.addEventListener(event, eventHandler, false)
+                );
+                ['touchstart', 'keyup'].forEach(event =>
+                    document.addEventListener(event, eventHandler, true)
+                );
+            },
+            deregister: () => {
+                ['click'].forEach(event =>
+                    document.removeEventListener(event, eventHandler, false)
+                );
+                ['touchstart', 'keyup'].forEach(event =>
+                    document.removeEventListener(event, eventHandler, true)
+                );
+            }
+        });
     }
 
     public isUnhandledKeyPress() : boolean {