finally been able to do more work on the transform gizmo for &half-edge (really bad timing on that apartment move :SCWWcrying:). I've now got basic handle mouseover detection going, and migrated the handles to be less coupled with the IMGUI loop! the things up next are:

• adding interactivity, to drag these cones for linear movement
• adding the lines for the arrows, so it's not just arrowheads
• adding planar handles for xy/yz/zx movement, and their interactions
• optionally adding modifiers like precision movement, as well as camera-plane dragging!