docs: 0.2.6.3 — what was measured, the manual, and Sunday's checks

Why black and white is made with Ghostscript and how close it is to what
Elmer prints; why Print image goes through the engine's copy image, with
the table of what each other way failed on; what it cannot reach (a CSS
background picture) and what it costs (the clipboard lives in Wonder Ink
afterwards). The manual says Print page and Print image, and that the
preview turns grey. Sunday's paper checks for both, in testing.md.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/testing.md

@@ -575,14 +575,14 @@ ifupdown stanza is already gone. **Do not run `--adopt` on it.**
       still reports `yes`
 - [ ] The laptop still reconnects after a reboot
 
-## Wonder Ink — 0.2.6.1 and 0.2.6.2, before either goes to stable
+## Wonder Ink — 0.2.6.1 to 0.2.6.3, before any goes to stable
 
 Everything below was done in the lab except what a lab cannot do: paper,
 a classroom's own graphics, a real keyboard, its network and its screen.
 Those are these checks. Stable stays on 0.2.2 until they pass.
 
 Before starting, on each machine: `dpkg-query -W ekklesia-classroom`
-must say `0.2.6.1`. The desktops only get it once stable is moved, so on
+must say `0.2.6.3`, which carries everything 0.2.6.1 and 0.2.6.2 did. The desktops only get it once stable is moved, so on
 a desktop install it by hand for the test:
 
 ```
@@ -600,14 +600,14 @@ after testing, either promote or reinstall 0.2.2 the same way.
 - [ ] Open Wonder Ink, sign in, open a lesson with a worksheet
 - [ ] Click the worksheet; it opens as a tab named after the file, with a
       document icon
-- [ ] Ctrl+P (or right-click → Print…): the preview shows the worksheet's
+- [ ] Ctrl+P (or right-click → Print page…): the preview shows the worksheet's
       own pages, page count right, ‹ › turn them
 - [ ] Printer shows **Elmer**, preselected
 - [ ] Print → a notification "Sent to the printer — … — Elmer", Wonder Ink
       stays open on the lesson
 - [ ] **The worksheet comes out of Elmer**, every page, right size, in colour
-- [ ] Pages `2`, Copies `2`, Black and white → exactly two grey copies of
-      page 2 come out
+- [ ] Pages `2`, Copies `2`, Black and white → the preview turns grey,
+      and exactly two grey copies of page 2 come out
 - [ ] Print a normal lesson page the same way; it comes out, Letter
 - [ ] Open the preview and press Cancel → nothing prints
 - [ ] Print three times in a row → three printouts, no crash
@@ -627,6 +627,43 @@ after testing, either promote or reinstall 0.2.2 the same way.
 - [ ] A worksheet PDF still prints with no Picture section
 - [ ] The print dialog says **Color**, not Colour
 
+### Black and white, and Print image (0.2.6.3)
+
+The lab measured all of this on the files CUPS kept, and under the real
+Plasma session for the clipboard. What it cannot show is Wonder Ink's own
+site (no account), real paper, and a classroom's own keyboard and mouse.
+
+- [ ] A lesson page with colour on it: Ctrl+P, then **Black and white** →
+      the preview says *Preparing black and white…* for a moment, then the
+      page is **grey**. **Color** → colour again. Back and forth three
+      times: it is instant after the first, and stays on the same page
+- [ ] Print it in black and white: **the paper matches the grey preview**
+- [ ] The same with a worksheet PDF (a few pages), in black and white
+- [ ] Choose Black and white, then Color, then Print → it comes out **in
+      colour**
+- [ ] In a lesson, **right-click on a picture** (not the words): the menu
+      has **Print image…** and **Print page…**. Right-click on the words:
+      only **Print page…**
+- [ ] **Print image…** on a picture you cannot open in a tab by itself:
+      the preview shows *that picture* on white, with the **Picture**
+      section — not the lesson page
+- [ ] Size **50%**, the **top-left** square, Black and white → the preview
+      shows a grey picture in the top-left quarter. Print it: **the paper
+      matches the preview**
+- [ ] Print image on a picture with a transparent background (a clipart
+      animal, a logo) → white around it on paper, not black
+- [ ] Print image, then **Cancel** → nothing prints
+- [ ] Copy some words in the browser, then use Print image in Wonder
+      Ink, then paste in the browser → the words paste, not the picture
+- [ ] If any picture says *could not be taken from the page*: note which
+      lesson and which picture. Right-click the same picture again once
+      the page has finished loading. If it still says so, that picture is
+      drawn in a way the engine does not treat as a picture — tell us
+      where it is
+- [ ] If right-clicking an obvious picture offers **only** Print page, the
+      site draws it as a background. Note which lesson — it is the one
+      case Print image cannot reach
+
 ### Size and zoom
 
 - [ ] A lesson in Wonder Ink is the same size as the same page in the
@@ -695,4 +732,4 @@ classroom-wonderink --diagnose
       says `false`)
 
 If anything here fails, leave the desktops on stable 0.2.2 and fix it in
-0.2.6.2 on canary.
+the next maintenance release on canary.