Initial MenuBarView Implementation

[jvalkeal]

Traditional "MenuBar" implementation which opens a drop box below a menu item.

Drop implementation would then be "MenuView".

┌─────────────────────────────┐
│ menu1 │ menu2 │ menu3       │
├─┌───────┐───────────────────┤
│ │ sub1  │                   │
│ │ sub2  │                   │
│ │ sub3  │                   │
│ └───────┘                   │
│                             │
│                             │
└─────────────────────────────┘

• Event when selection changes
• Event when selection is selected