this method is to be called whenever someone click on
the "New Event" button of the toolbar. It will instruct the active
view to generate a GcalView::create-event signal with the parametes
of the current unit (a month for GcalYearView, a day for GcalMonthView, etc)
It will allow the view to mark the current unit cell for the event creation.
Added GcalView::update signal for when the view will change it's date range
Added GcalView::create-event signal for when the view wants to create a new
event
Added GcalView::clear_selection method for clearing new-event mark.
Note: The views can choose to mark before send a ::create-event signal the range
over which they will create the new event. This will be called new-event mark.
Added ::active-date property
Added set_date/get_date pair of methods for handling the property
Added get_initial_date/get_final_date pure virtual methods.
Added GcalEventView::will-delete to let thw window knows about the change.
GcalWindow will handle the hiding of the event-widget till the notification goes
away or the user click "Undo".
Added method in GcalView interface to retrieve and event-widget by it's uuid.
Added some cosmetic changes in GcalMonthView as well.
Created GcalView interface, used in GcalMonthView
Added implementation for GtkContainer virtual funcs in GcalMonthView
Improving size_allocate/drawing methods
Added day selection drawing
Added gcal_view_add_event method GcalView interface.
Fixed size_allocate implementation in GcalMonthView to allocate children events.
There's still work to be done here.