Hi, I've been breaking my head for the last few hours trying to find a solution to this. I know this may be late, but this is the best solution I've been able to come up with.
Honestly I don't know why this isn't posted somewhere because it works perfectly... it basically "disables" the "Highlight Existing Fields" button... the bar and button are still there, it just won't allow users to effectively use the button.
I placed the following code at the topmost element in the Hierarchy, in form::ready.
topmostSubform::ready:form - (JavaScript, client)
app.disableHighlighting = function() {
app.runtimeHighlight = false;
}
var timer = app.setInterval("app.disableHighlighting()",700);
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Basically, it disables field highlighting at an interval of 700 milliseconds (even if already disabled). That way, when someone presses the button, it will immediately get disabled... thus, button = useless :)
Hope it helps someone.