Right click on a widget loses editable selection

[markcharyk]

Steps to reproduce

1. Go to the demo page
2. Select some text including a widget (a reliable spot I used was selecting the header "broadcasting and quotes" including the anchor widget at the end)
3. Right click on the widget

Expected result

The context menu appears and you are able to cut/copy/paste/etc your text selection

Actual result

The selection is lost as the widget gets focus and you can't use the context menu to access the previously-selected text

Other details (browser, OS, CKEditor version, installed plugins)

I reproduced this on Chrome 44, but it seems to happen on all browsers, the one difference being it happens on right-mousedown in Chrome and Firefox, and on right-mouseup in IE11. Our app has context menu options beyond cut and paste, specifically some we use to operate on a custom widget and surrounding text, so this is a noticeable issue for us.

[Tade0]

I dealt with the problem by preventing the selection from being changed when a context menu is invoked.

Changes pushed to ​branch:t/13719.