@Anonymous.DeFlaminis , directly related to these overall UI issue, but apparently not changeable. Took me a while to figure out why I was constantly making the mistake of not realizing an edit poly (or any modifier) sub object is selected, and clicking around trying to get max to respond. In the UI, "modifier selection" highlight used behave this way, using Edit Poly as an example (pictured in the attached):
If you select the edit poly modifier in the stack, it has a solid highlight.
If you open the sub-object rollout, whatever sub mode you have selected has a solid highlight.
If you have a sub mode selected, but the rollout isn't open, the edit poly modifier has the solid highlight (plus the highlight in the modifier rollouts)
When the object was selected, but no sub-object was selected, the top modifier was highlighted in a different color.
Now, in that same scenario, if the sub rollout is collapsed, the edit poly modifier is still highlighted, but it's just a border that is incredibly easy to miss, especially in the peripheral vision. When the sub-object isn't selected, the top stack is highlighed like I would expect it to be the reverse. I'm wasting at least 2-3 minutes an hour not realizing I didn't deselect sub mode, and it's driving me even more batty than the remaining unchanged icons....
As you can see in teh attached, it is REALLY hard to see that the edit poly is selected; this is even more the case when the selection rollout isn't open, or in a modifier like symmetry, which doesn't show in the rollouts that the mirror axis is selected.
<Kris tears out his hair> I'm hoping there's a place one can change this that I'm just missing. You can change the color in Customize UI>Colors>General UI Colors> modify selection, but not how the fill operates.