Dynamic highlighting greyed out

I have an assembly where the dynamic highlighting option (Tools, Options, Display/Selection, Dynamic highlight from graphics view) is
greyed out. It is checked, but I can't change the setting. And it isn't working. Not dynamic highlighting, no smart cursor, no clue what I'm doing wrong. Any ideas?
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Is large assembly mode active? That is often the culprit when stuff in assemblies is grayed out.
Jerry Steiger Tripod Data Systems "take the garbage out, dear"
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Yep, that was the problem. Kinda wierd though. Never had this problem before. Also, there were 719 components in the assembly, and Large Assembly Mode was set to 2000 components. Also, I can sort of see turning off dynamic highlighting, but turning off the smart cursor also? How do you have a clue what you are going to select during mating, for example? And shouldn't there be an option in the LAM options to toggle these on and off as the user sees the need?
Anyway, thanks for the help.
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