In the Learn tab, when you select heroes from each of the categorys (Radient/Dire Str/Agi/Int), it will create the normal white box to highlight which hero you picked. But when you select heroes in different sections, the old box will stay enabled.

In the attached screenshot, notice Omni, AM, Storm Spirit, Spirit Breaker, Spectre and Shadow Demon have boxes. Moving to a different tab and returning to the Learn tab does not remove the boxes, only the preview of the selected hero.
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