Gray-out custom property fields when needed

I would like to see a feature added to allow custom properties to be disabled/locked-out where appropriate.

For example, let's say we have a "Base Object" which has two custom properties. One of them alters the position of a nearby cube, while the other alters the position of a neighboring sphere, so that one or the other can intersect with Base Object.

Neither the cube nor the sphere *have* to intersect Base Object, but they also aren't allowed intersect it at the same time, so the drivers that move them around would be set up so that if both of their associated properties are changed, only the cube will move; the property that moves it overrules the property that moves the sphere. Of course, the properties' tooltips would mention this limitation.

But, that leaves one issue: the project file containing these things will be distributed to others, and inevitably some new user will ignore the properties' tooltips and try to move both shapes... but the sphere refuses to budge, and they can't figure out why. There really should be a way to let them know that the property that moves the sphere is being ignored at the moment.

A UI coder would normally do that by graying-out the offending number field (and perhaps also hiding its value).

Since a custom property's value can itself be set by a driver that's taking its inputs from other custom properties, it seems logical that all that's needed here is another type of driver that only affects the UI element itself, rather than its value.

One could, say, right-click a custom property's numeric field and select something like "Add UI driver...", which would give them the same driver editor they're used to, with all the same features every other driver has, but its output value would be used to lock-out the numeric field the user right-clicked on (e.g. if the driver's result is non-zero).

Perhaps if a field is grayed-out, the user might be prompted to hover the mouse over it to read the aforementioned tooltip... Or at the very least, they would notice that changing one field locks-out the other.