Emulator

Datel's Wii Freeloader supposedly should show solid colors, but nothing is shown in Dolphin. Could be because of this feature not being implemented.

I don't think that's related. http://uk.codejunkies.com/support/article.aspx?article_id=389 says that it was updated to give a clearer indication compared to the colored bars (but the instruction card wasn't updated?), and http://uk.codejunkies.com/support/article.aspx?article_id=394 clarifies that you either get colored bars or the more clear icon (3rd paragraph of section 3). I installed System Menu 3.1 from Wario Land: Shake It!, and with the copy of freeloader I have, I do see the screen flash with that image briefly (along with a buzz from audio not being muted), although freeloader itself doesn't seem to work.

Based on my understanding of what HW_VISOLID does, it wouldn't be capable of producing colored bars, but only a single solid color. So they probably didn't use HW_VISOLID in the original version either, but I only happen two own two otherwise-useless Wii Freeloader discs (one US, one EU), and probably don't need to hunt down a rarer third one :P

Oh, so the Datel documentation said colored bars. Okay, I was misremembering then.