Havoc has pushed a new version of their Map Editor, today.
The update reimplements colour selection for map symbols, and far more importantly fixed a small problem with support for Corridor 7.

Given that it is Corridor 7’s birthday today, the release is well timed.
Havoc’s Wolf3D Editor (HWE) is capable of editing almost every game built on the Wolf3D engine (excluding ROTT, sadly), and runs on modern Windows systems.
Havoc’s Wolf3D Editor download
HWE on Havoc’s Wolf3D Page
HWE on WolfSource