Compose window font settings

I’ve been troubleshooting the compose‑window font behavior in Thunderbird and discovered something that seems inconsistent from a user‑experience standpoint. After resetting all the font mappings (Proportional, Serif, Sans‑serif, Monospace, Minimum font size, etc.), I noticed that the font used in the message body can never match the font used in the Subject line or the rest of the Thunderbird interface. The Subject line and UI elements use Segoe UI, which is the standard Windows system font. However, Segoe UI does not appear anywhere in Thunderbird’s compose‑font dropdown lists, even though it’s clearly installed and used throughout the rest of the application. This creates a confusing situation: - The interface uses one set of fonts (Windows UI fonts like Segoe UI) - The compose window uses a completely different set (web‑safe/message‑safe fonts like Times New Roman, Arial, Courier New) - The user cannot choose the same font for both areas, even if the font is installed on the system - The dropdown lists in different parts of Thunderbird do not match, even though they appear to be selecting fonts from the same computer From a user perspective, it would make much more sense if all font dropdowns in Thunderbird used the same unified list of system‑available fonts, so the user could choose consistently across the entire app. Right now, the separation between UI fonts and message‑body fonts isn’t obvious, and it leads to confusion when trying to restore defaults or match the appearance of the Subject line. I’m posting this to ask whether this limitation is intentional, a technical constraint, or something that could be improved in future versions. A unified, system‑wide font list would make the experience much clearer and more predictable for users. Thanks for any clarification Steve