Merge pull request #83 from GuillaumeGomez/master

New trait : Actionable
Merge pull request #84 from GuillaumeGomez/master

Fix event structs errors
added get_window_set_decorated() toset and remove Window decorations
toggle window decoration on in gtktest
Merge pull request #85 from buster/window-decoration

added gtk_window_set_decorated() to set and remove Window decorations
New trait : GtkCellLayout
Development in progress