It’s disconcerting when a panel plugin is selected from the plugin list, and its accompanying icon just disappears.
The “principle of least surprise” would leave that icon next to the plugin name on the upper left, just like it appears in the plugin list. And the user loses a critical contextual & visual clue as to what’s running in the panel–she has to read the tiny plugin name to really know.
For now, we have to display our own plugin icon somewhere at the top of our panel content, which seems wasteful and will only be done inconsistently.
Oh, and also, can you bug them about using a higher-resolution icon in the list (and now the header)? It’s still low-res in XD 22, after it was pointed out months ago.