The .ui files are all GPL-3.0-or-later style, but it's
slightly difficult to keep licensing information in them:
it's XML, so an XML comment might work, but there's no
guarantee that safe/load will preserve them.
Put the SPDX tags in the <author> tag, so that it's visible
in Qt Designer.
- Move layouting code into the .ui file
- Reduce margins hugely -- atop the title block, around the
scroll area, etc -- so that more license is visible at once.
- split shared <h1> message off
- do some string-concatenation, but only of whole sentences
- shave off some vertical space by dropping the mainsubtext item
