Double bonds have rendering problems

[Krzmbrzl]

When using double bonds (or triple bonds for that matter) there can be problems when the geometry of them is not linear: They tend to intersect with other bonds or don't even connect to the other bonds because the double bond is bended (by e.g. ~90 degrees).

You can verify that by creating a propane structure and adding a double bound to the C2 position and then dragging that C2 position around.