Place two models on one view

Hello all. I need to do some interesting feature, and I hope you help me. I have some models with dates, for example project, task, resource.leaves, my custom models, etc. And my customer wants to see all this records on one gantt-view. For example, if I need to place task, I need to see resource.leaves to prevent placing task in busy employee's time. Openerp documentation says it is impossible. But this is nesessary feature, and in spite of documentation I will trying to realize this. May be somebody already released this, or have been trying to release - I will glad to see your experience.