I was hovering over Tu’Rani’s Bident and hovered over an Idol while holding down ALT and the following happened:
It was still comparing the spear to my currently equipped items, though it was transposing the text onto the Idol’s text.
The other screenshot is a related bug that happened at the same time when I wasn’t holding down ALT while trying to replicate the bug mentioned above. This one likely happened because the spear’s text (along with the comparison of stats) is so large that it was forcing the text for the Idol down off the screen.