`Download & Write` presented as `Download _Write` in GNOME

[larouxn]

On the latest version of writer, I am seeing Download _Write in Fedora GNOME. This is without pressing alt. I believe mnemonics are only supposed to appear when pressing alt so this behavior is both surprising and doesn't look great. Looks related to the proposed changes in #655 and issues/643 but this is happening in the released app. Thus something must be in the existing codebase.

[grulja]

This might be a bug in Qt itself in the Fusion style, because it doesn't happen with Breeze and I think it doesn't happen on Windows and macOS.