Sets or gets a value that indicates whether the document can be edited.
Starting with Internet Explorer 11, the returned property values are lower case rather than capitalized.
You cannot execute script when the value of the designMode property is set to on.
You can use the designMode property to put Windows Internet Explorer into a mode so that you can edit the current document.
While the browser is in design mode, objects enter a UI-activated state when the user presses
ENTER, clicks an object that has focus, or double-clicks the object. Objects that are UI-activated have their own window in the document. You can modify the UI only when the object is in a UI-activated state.