Before I start, has someone mentioned how great iNotes is? Well, if not: you did a really great job with this! Full and Lite (now with the quota gauge) are state of the art application modes.
Well, back to the issue. Very small one. When in Full mode (FF3.0.1) and switch to show the preview pane right, the “inbox-folder” now shows the sender and the subject in two rows. Doing so, the first column (which contains the icons) shows small lightblue blocks (empty or with icons). But the blocks are seperated with space (few pixels). For example: if you highlight a mail by choosing it, the blue color is “behind” these blocks. Due to the space you see the blue shining through. So, there is a small issue with the css positions or the need to choose transparency (show the icons with no background-color will solve it).