Since upgrading to the DOpus 10.2.0.1 Beta, I've noticed custom icons in the "My Computer"/Tiles view are rendered smaller than the default Windows icons:
Is this a known bug? Easy fix?
I don't think anything to do with icon sizes changed in 10.2.0.1, and it must still be working as the first two icons are drawn large and there's no difference in how custom and standard icons are drawn.
Do the custom icons have 256x256 versions within themselves?
Hi, Leo —
I just found a note reminding myself that I got busy and never followed up. 
(Hooray for New Year "To Do" List Sorting Day!)
For what it's worth, my custom icons include this odd range of sizes: 16x16, 32x32, 48x48, 96x96 (?), 128x128, and 250x250 (??). Lord know what I was thinking back when I iconified those images. Maybe I had someplace where 250x250 was used and never though I'd need the more-standard 256x256 size? (Or maybe I just didn't have images that large for them?)
At any rate, it looks like I'd somehow tweaked the My Computer view to display 128x128 icons in the past and lost that setting somewhere along the way. Now Opus is displaying the 256x256 versions of icons for Windows' default icons (the drives) and the nearest standard size (128x128) in my custom icons — ignoring the oddball 250x250 size.
Maybe earlier versions of Opus just used the largest version available in an .ICO file? Either way, it's a nice wake-up call to revisit my icons and clean 'em up — which is now adding to the 2013 to-do list!