I've noticed that when selecting text and choosing to format it, the format options don't show feedback to indicate the existing formatting applied.
For example, I high lighted some text which looked different to other text on my diagram, not sure if it was a different font size. When I went into the B/I/U dialogue, nothing was indicated. I clicked bold, and saw the text return to a lighter weight, so I realised that it was accidentally set to bold before.
The B/I/U dialogue could indicate which format is currently applied.