In some cases TitleView dissappears while resizing. Now it only
disappears if all fixed sized elements of ContentView together (a struct
counts only one time) need the space of TitleView while resizing.
Add border functionality.
Tidy up a bit GUI.

-> Resizing
-> Buttons
are still missing!
GUIStyle removed
Merge branch 'fix_TitleViewDisappears'
Merge branch 'feature_RestructureRootView'
Merge branch 'fix_ViewExtDialogue'
Updated ContentView