Creating Custom Axes Of Rotation
Could it be made possible to define your own axes of rotation (see the
illustration I sketched with Paint).
In the drop-down menu, where the user can choose the axis (x, y or z) about which to rotate the selected objects, an additional selection of "user defined" etc. could be added.
After having selected "user defined", more options would appear on the rotate tool (see illustration), with which the user can type in the two points that define the rotation axis. Alternatively the user can set the points by clicking on the map. (It would be nice if the center of rotation, too, could be set with the mouse, btw.) :)