Eraser tool doesn't work consistently in ghost block mode.

[pjw]

Repro:

1) Open the Stadium editor.
2) Enable ghost block mode via Advanced Customization Tools and toggle it on.
3) Place one block 5-5-6, floating in mid-air.
4) Turn on the eraser tool and attempt to delete it from various angles.
5) Notice that the block will only highlight from specific camera angles and positions.
6) Notice that the block will only highlight when the cursor is over certain parts (material/trace problem?).

For a more extreme example, place block 5-1-1 while in ghost block mode and notice that it cannot be erased/highlighted AT ALL.
You can only Undo.