TimeLine : public Widget

Okay... l'éditeur d'animation prend forme, mais on est encore loin du compte. Disons plutôt que j'ai enfin une base sur laquelle travailler le comportement de la "ligne du temps". C'est terriblement "prototypal" ... arithmétique de pointeurs pour configurer les sprites, et tout le tintouin. Il y a sans doute moyen de faire plus propre, mais je vais le garder tel quel jusqu'à ce que les éléments soient tous en place et que j'y voie un peu plus clair.

Slowly, the animation editor is shaping up. It's still far away from the objective, but at least I have now a more solid base on which I can work on the "timeline" widget behaviour. It's still very sketchy : pointer arithmetic circumvent the lack of proper OO containers or patterns ... but at least I can make the thing exist, grow up, and have a clearer view of what I still need.

A running list of things to work on:

• [done] new frames added on the timeline can easily go out of the allowed width for the widget.
• [done] moving frames along doesn't affect the animated version.
• [done] we don't have any visual confirmation of the frame we selected.
• [past] animation always start with a delay and can't end with a delay.