Well, it looks like this answer might be wrong. Now I think that the enclosed alphanumeric characters and friends might be fullwidth forms, similar to the CJK unicode characters. This would explain why Ⓢ takes up exactly two spaces when using GNU Unifont.
In which case, this might best be filed as a
If you notice, each company entry is the full word, followed by some variable padding, followed by the character, followed by exactly one padding space, followed by the space for the scroll bar. Perhaps company can leave out one padding space for each fullwidth character in the entry.
DejaVu does not include the circled S character (
U+24C8), or any other circled characters other than numbers1. Emacs is falling back to another font to display the character. You can determine exactly which font by calling
describe-char with the point on the character.
This fallback font is wider than DejaVu or Monaco at the same height, which gives you the behavior you're seeing. You can change fallback fonts with fontsets. Here's a relevant SO question on this topic. Perhaps you can configure the fallback font to use a narrower width (if that is supported by the font). Alternatively, you can install and specify a new font that includes more characters to fallback on (maybe with the same height to width ratio as DejaVu?)
According to Xah Lee:
DejaVu has significantly more Unicode symbols than other popular fixed-width fonts
So you may be out of luck finding one unicode-complete monospaced font.
GNU Unifont includes all characters in the Unicode BMP, but I think it's pretty ugly.
- These are called Enclosed Alphanumerics. You can find DejaVu's coverage in their SVN, including specifics of which characters are covered.