There is no more automatic detection of units to draw ranges for, there is a unit list now for each supported mod. Currently CA and BA are supported. Adding support for other mods is easy as pie.
-Displays ranges of ally and enemy defense buildings. (Ground/Air/Anti-Nuke)
Enter tweak mode by pressing CTRL+F11 and you can drag the buttons position around to fit your needs.
See following image for an example:

Feature requests and bug reports are welcome.
Thanks to the Lua guys for helping me out!
Props to Evil4Zerggin and Marmoth for code samples!
Changelog:
v6.12
-bugfix (BA Ambusher working again)
v6.11
-BA: added (missing) water defenses: TorpedoLauncher, Float-HLT, Float-MissileTower
v6.1
-TweakMode fixed
-XTA-Support (thx to _manolo)
v6.0
-all functions besides range drawing removed
-combo units having ground and air weapons are correctly drawn using two circles
v5.11
-updated: you now have to press meta-key (space) to see blast range when placing buildings
-updated: EXPLOSION-text replaced by explosion's default damage
v5.1
-added: displays blast radius when placing buildings
-added: hides gui correctly when pressing F5
-added: tweak mode added to move buttons around when pressing CTRL+F11
v5.01
-fixed ghosted features
v5.0
-Improved accuracy of range circles
-More accurate DPS-colors (using BurstFire)
-ghosted features
-fixed Air for BA
v4.13
-fixed: green ghosted buildings do not disappear
-small bugfixes and refactors
v4.11
fixed glBlending
v4.1
added: GhostedBuilding for nano frames
fix for CA
CA/mod specific color config
v4.0
added: new unitFile system
added: optimization and rewrites
added: range color depending now on dps
added: units can have more than one weapon (like Doomsday in BA)
added: dynamic line width and alpha depending on camera height
added: selfd-radius AND explosion-radius are visible
added: remembers button states from last game
fixed: in team games markers get set only by one player (no more multitagging)
fixed: BA armclaw and cormav fixed
v3.7q (thx to quantum)
fixed for CA
performance improvements
v3.7
added: Press meta + X to see selfd blast radius of selected units ("meta" is by default the space key) -> Space + X
v3.6
fixed: bug of disappearing ranges (hopefully, pls email me if it still happens )
added: buttons now resize depending on resolution
added: new weapon detection method depending on static unit files
updated: opacity of drawn range circles reduced to 0.1 which is more subtle
v3.4
fixed: works now with spring svn version (>0.75b2)
fixed: some unit detection glitches (Screamer/Mercury in CA)
note: XTA works with svn version
v3.3
fixed: Juno does not get marked as Nuke any longer (thx to Klopper)
v3.2
fixed: Renders correctly on ATI now
fixed: AntiNuke/Nuke gets marked again
fixed: Widget gets disabled in spectator mode
fixed: some speedups
v3.1
-fixed: AntiNuke (sorry)
v3:
-added: support for combo units (ground and air -> CA)
-added: support for different mods, especially CA (XTA does not work properly)
-updated: new icons
-updated: unit de├óÔäó┬ªtection (more accurate now, at least I hope)
-updated: code cleanup
v2:
minor bugs fixed (killed inclusion of opengl.h, correct resetting of OpenGL parameters)
Download at SpringDownloader or at:
http://spring.vsync.de/luaManager/