[Doitsu]

@DiapDealer & @KevinH: I found out that it's relatively easy to generate a Qt help file from the user guide without any code changes, except for converting non-ASCII characters to HTML entities.

All you'd have to do is, unpack the user guide, copy a Qt help project file to the OEBPS folder and run the Qt help compiler.

To generate the help file:

1. Unpack the updated user guide epub file.
2. Copy sigilhelp.qhp to the OEBPS folder.
3. Go to the OEBPS folder and run the following command:

qhelpgenerator sigilhelp.qhp -c -o sigilhelp.qch

To preview the Qt help:

1. Open Qt Assistant.
2. Select Edit > Preferences.
3. Select Documentation > Add > sigilhelp.qch

(I created a Qt help file and attached it and the help project file.)

Note that the existing user guide contains the following non-ASCII characters that need to be converted to entities before running the help compiler:

copy, mdash, rarr, ldquo, rdquo, rsquo, rarr and ge

I used DiapDealer's ShadyCharacters plugin to convert them to entities. Here's my plugin preferences file:

Spoiler:

{
  "matrix": {
    "ge": [
      "0x2265",
      "≥"
    ],
    "zwj": [
      "0x200D",
      "*"
    ],
    "shy": [
      "0x00AD",
      "*"
    ],
    "zwnbsp": [
      "0xFEFF",
      ""
    ],
    "nbsp": [
      "0x00A0",
      "*"
    ],
    "rdquo": [
      "0x201D",
      "”"
    ],
    "thinsp": [
      "0x2009",
      " "
    ],
    "rsquo": [
      "0x2019",
      "’"
    ],
    "rarr": [
      "0x2192",
      "→"
    ],
    "nnbsp": [
      "0x202F",
      " "
    ],
    "mdash": [
      "0x2014",
      "—"
    ],
    "wj": [
      "0x2060",
      "⁠"
    ],
    "ndash": [
      "0x2013",
      "–"
    ],
    "ldquo": [
      "0x201C",
      "“"
    ],
    "copy": [
      "0x00A9",
      "©"
    ]
  }
}

(Not all of the entries in the list were actually used.)

and here's the corresponding Sigil.ini section:

Spoiler:

preserve_entity_codes=\xa9\x2014\x2019\x201c\x201d\x2192\x2265\xa0
preserve_entity_names="©", "—", "’", "“", "”", "→", "≥", " "

I don't know how difficult it would be to add Qt help viewer support to Sigil, but it couldn't hurt to investigate this idea.