     }
   }
 
-  public mutating func on(eventType: SEventType, fn: SEventHandler) -> Int {
+  public func on(eventType: SEventType, fn: SEventHandler) -> Int {
     if eventStore == nil {
       eventStore = EventStore()
     }

import _Sua


public protocol Element {
  var type: SType { get }
  var maxWidth: Int { get set }
  var maxHeight: Int { get set }

  func drawBackground(x: Int, y: Int, width: Int, height: Int,
      strings: [String])

  func on(eventType: SEventType, fn: SEventHandler) -> Int

  func signal(eventType: SEventType, inout ev: SEvent)

