exemple : https://app.diagrams.net/?tags=%7B%7D&title=toto#R7Z1vc9q4Foc%2FDXNf9Q6WgZCXwJLszpCGgbL7suPaCqg1FivLJNlPfyVLBv9lbQfK4VYzaR3LtrB1Hp%2BjI%2BlHOvZk%2B%2FbInN3miXrY76Cu99axf%2BsgZN33LLGRJe%2BqZGDrgjUjnj7pWLAk%2F2Bd2NWlEfFwmDmRU%2BpzsssWujQIsMtVmb7WYYy%2BhpmiF%2BpnP3XnrHGhYOk6frH0L%2BLxjSodortj%2Be%2BYrDf6ky1rcK%2BObJ3kZP3R4cbx6GuqyJ527AmjlKvftm8T7MvGS9pFXfdQcfRwYwwHvM4Fv1vjL48zUTB7VpfuHT%2FCFcdC%2Fp60QPhKtr4TiL3xCw34Uh%2Fpin13Q3xv5rzTSN5ByB33R7I33lBG%2FhHnO744ZImCjrw%2F%2FSNOZVwb2%2B5mzl7KWnT9DIfinHnyiFau6Ml5y5w4c0KuC9Iflv5xqe87u5B8OzzD1mFrEowp53Sri3aU8QkNQs4cEvAF5Q4nNEg%2BSu46x%2Bs9RndfRB2Yp%2B8ldYJstAdnS3z5BmxpQMOd4%2BL4HvMG1DbdY8bxW6pIG%2FQR0y3m7F2coo%2Fa1n%2F76hr9elkJba9HWK07DesmBWof6XdEvx%2FrQ91HhMQvmqJ4dxVi9vztu3zLUNd3vmFfw%2FNofRYl89FC%2FP9J%2FHucjvRv49WX7EurrlBFWTC%2FflX1oBy%2BKRJFo0iyhF3oDzyhPmWiPKAKTeL7uSLHJ2tpNR%2B%2FyMtkqxLxYo908ZZ4no9zrFBx1osfv6YbcRwHMQ6CgriZ%2BmPxI06bdEWz98UtTcS%2BddwXP9XoZakS1WGB6yuWyBag8qn7A3sa%2BUqA5JYE61n8fL9Z3VKmiq%2F9v9OlYUKDeiwl5zVgSeymcKpwWIKHKn%2BVO2Tc1U24q093GWd1cEIpwFC%2FVwTsbnhWZ7WYirLF9EvBXS06E7szug8jXzRabfclWVTeS1Zs%2FNeZ%2FVfeC3zEfZXSdR73dQq45WouClcPBeDmThjKDmiMGmqCWlylYQ0Ka3U92aVCZaoLpf6vCJyFcIk9ke7o3RCvt6ItpseiMQ68kcyixFHXF7ASV0Y%2Fvk2ipBuxfdz4KtZEgXcwRdqeohodPocxlMdwOsxbsDLMhDRiLi4%2Br35rkphWYkb5jCeNmLJav1vSV9ZlDPsitO6zmWEDS5b2cBbTE32c7EHTy7mNXg4aZro5vWQsI%2B0c7gdFzqx%2Bc%2B9wIuxMLEsGlslEB5s%2FhIvm5IVgJp%2BQUReHoXTjbO2ITb2OjgAyfuviuk34OX%2F4ybmDD3V2yhi7eGdnYqFq6jzVwXZJKN%2Fd5tAhAx0k6Mp6PVeCzq6GToVt0bItgLMNcJCASwYCrg3ccvoUx9ZZAtwxpVtanSZjn0faVJ2GNji0Wd0eGNxQFW6oPW4mmsLCza6ZJ1xyvD0ZyEy2%2F%2BfjCPmx2%2BJAQrYJIA8liJyseighd9AMJdzGUEL%2Frpeb4R30SjK9ISqidt5Jk1U8mLCa6mgzChz%2FPSwfSVjWikMSyPjNW5mhhIvEobw7%2BNBQQhlgF8%2FqVqg%2Bc7UmT47MIcMcKObKRhIux1x59ESnoicy0fP2oqfAqk70tO3LR0%2BU8WTEKx0OrRs5URI5TQZ3GS%2BGzhc5y%2BD6CZGzHm81o2bCGzK8geKtLGpejrfyqGmfipq2iZo3FzVRt07MvPwyvVU8p3PwYXPiU16Yz6kbMe0kYpoJnct4MPt8EfMqa%2FRWqA5tNeNlQhsytIGi7dqr9OI5vsp4mT9o4uVNxEvbqjNEayeLwDKzAfdnjZjj589ywOx5nqxsH9Mgqh0lY%2Fxiv6XqMY7r3I6r8PZ%2FJEyWAnXxMDl%2FkIQ9jRLC5qItX6hPaHPK4qoMZHAgK4mO14Fs0bW6WcymwZ4wqfCV88qygdU4Bv3UDDldsYEODnQlK7quBx06Cd33iBGP%2FB3hFtSZgTNQ1JWt7LoednYGuwUO1RIV2XPbRFvRqDhsgZzJPWEhV7K663rI9TLIPTmBs07cnNeZoM74wXE52ROuFbEt%2BOsZ%2FkDx14eSQ0g4%2BicjbUhd0qZv1zfIgUIuWcEBArlBBrkHEgpjJv6tBWsDwxok1lAXUiJxl2FtQrc70WTkI7jdGdxA4WZDSiCGGdyeI058mTzIryBrgdrQoAYKtQGkxOG%2BHLUg2irXxuQASZt04d5QB4q6IaB0QX5upu8WOIHbYhhO3b%2BBDApktgUoQbCyUw6PouXUKklPfj%2FTjtHvmLdAzsw3wELOBpQnWNkJh3n47m6EwddEEicHQRy%2FjZczkw2wkBsAyhWs7GTD9G3HcKiWgz%2BIPHXbAjcz0QALt3tA%2BYKVnWgYBWvfITJhcHa7FqiZOQVQqPUsSElCdk5hPp%2B3AMzMIMACrAcmQRjN7GyCMPsTKT%2Fmk78jNfjRuLOmKjXEASJuACY%2FEHBk8wMp41PIyWcl8VcHNx5qU7Ua5AAhdw8lP1jm110%2BWp%2BWI6mJWRIeYdaQtaVZbQkMtT6Ckhss86stD6g9kVB6OSyH3iiO9qxpVF2a5ZbQsKsriPkZ2Nnl2KkmjUgb3MwICCzc7n5q1lCu86v%2BNpn8QaPzuwmd32AASOcnKyvR%2BaF6ngsddH4mUF7Gc53vC2SupfMr9M4yUr9moMW1Gc7gcAZI6ofqSv2aIacrNtDBgQ6Q1A%2FVlvo1p864OlDUQZL6oVpSv%2BbImfwTFnKApH6oudSvOX9mWh4Wf4Ckfign9cvprpqzZmboYbEGSOOHchq%2Fou6qOW5G5gcKN0gyP5ST%2BWV1V81RMxI%2FWKgBkvihKolfVnfVAjoj9oMFHSCxH8qJ%2FURTciZpG%2Fd8OUMfL0ZaK5lMC%2FKM4A8WeYAEf6hc8Bczl%2FzRl%2BbEGfUfLOIgqf9QTv1XLsVqjpyZgoCFHCD1H8qp%2F4pSrOa4mbkHWLgBUv6hnPLvKMUa7XYtUDNzDrBQA6T6QznVn5RiNQfMTCqAAgyQ1m80QzWkWA2JU5Ua4gARB0n8h7KdtSdFGd9Q75AlpL8npDl8pusGCz5IOkBkV8EXD4d4%2F8GB9nsj3nwBiarfwAcIPjiKwPzyzINYhjPyTUoCm8G2NKsygbEGSBKYX5WpWPvDk2LnF9KGNRNUYbEGRweYX4p5VDpzZy07cg0lDkuzChMabFdXAVqfF1NFx8Sykm2FLFAVpHjB3hon%2Br8Qr%2BWKzemxaIwDb8RYbGvXd8KQuKJww7eJAtCN2D42gtLRRYF3MEnarqIaLQ0cxnAepYLDvCWL1tESOrWEufSh9SuUSPbUCblGkA960p4p%2B%2FVLzJeUqT%2FUuceZe2tg038xIEq2v5IBUYUB0Q0a0E62v5IB7QoD2rdmQKkGT7a%2FjAHlw5YZMN8IN2JAlGx%2FJQOWutB8I0AxoNhllPLUsUfm7DZP1JN95%2Bn%2FAA%3D%3D
Il ne reste plus que le problème des flèches qui partent "tout droit", je pense qu'on peut résoudre le pb comme dans la branche improve-layout, en décidant si on part à gauche ou à droite