456 - Time indicator tooltip on keyframe drag and drop operation - progress

- add moving_tooltip_ a Gtk::Window* Widget_Keyframe_List private member
- creation and setup moving_tooltip_ in Widget_Keyframe_List contructor
456 - Time indicator tooltip on keyframe drag and drop operation - progress2

- add user_display_ a Glib::RefPtr<Gdk::Display> Widget_Keyframe_List private member
- get the pointer coordinate from user_display_
- show and move the moving_tooltip_ gtk::window when draging keyframe
- hide the moving_tooltip_ gtk::window on mouse release event
456 - Time indicator tooltip on keyframe drag and drop operation - progress3

- add moving_tooltip_label_ a Gtk::Label* Widget_Keyframe_List private member
- setup moving_tooltip_label_
- add moving_tooltip_label_ to moving_tooltip_
- update moving_tooltip_ setup
456 - Time indicator tooltip on keyframe drag and drop operation - progress4

- displaying the dragging time
456 - Time indicator tooltip on keyframe drag and drop operation - progress5

- display the dragging time according the global fps setting
456 - Time indicator tooltip on keyframe drag and drop operation - progress6

- cursor position from GdkEvent x_root and y_root (remove Gdk::Display stuff)