VR keyboard: small Entf hint on the Delete key without AltGr

The key that becomes Delete on AltGr shows a small hint (the arrow hints'
7 px) on the baseline of Steam's AltGr hints, while the layout has such a
free key.

README.md

@@ -461,8 +461,8 @@ reboot or Steam restart needed.
   Shift + arrows select text.
 - AltGr + the key left of Backspace (`´` on German, `=` on US): Delete,
   labelled like Steam's Delete key in its language (`Entf`; `Del` if that is
-  longer); repeats while held. Layouts with an AltGr character on that key
-  get none.
+  longer), hinted on the key without AltGr; repeats while held. Layouts with
+  an AltGr character on that key get none.
 - Ctrl/Alt chords and Esc are sent with `xdotool key` on `:0` (focus follows
   the VR-selected window); a toggled Ctrl/Alt is held down while the
   keyboard is open (e.g. Ctrl+scroll).

modules/steam-keyboard-patch/patch.js

@@ -21,7 +21,7 @@
 // mkPatch patch (see lib/default.nix); no options. On a signature mismatch
 // it returns an error and changes nothing. Idempotent.
 ((find, sigs) => {
-  const VERSION = 14;
+  const VERSION = 16;
   const send = (msg) => window.__vrkbdKey && window.__vrkbdKey(msg);
   let mods;
   try {
@@ -95,19 +95,24 @@
   // its type with an empty AltGr entry.
   const keepSize = (x) => (Array.isArray(x) && x.length < 3 && first(x)?.type != null
     ? [x[0], x[1] ?? null, { key: '', label: '', type: first(x).type }] : x);
+  // Without AltGr the free key shows a small Delete hint (stylesheet, like
+  // the arrows' AltGr hints), enabled by the class vrkbd-del-hint on the
+  // keyboard document while the current layout has such a key.
   const withDelete = (rows) => {
     const kb = window.__vrkbdRendering;
-    const altGr = active(kb?.state?.toggleStates?.AltGr);
-    if (!kb || !(altGr || kb.__vrkbdDelHold)) return rows;
+    if (!kb) return rows;
+    const bsRow = rows.findIndex((row) => row.some((x) => !Array.isArray(x) && x?.key === 'Backspace'));
+    const i = bsRow < 0 ? -1 : rows[bsRow].findIndex((x) => !Array.isArray(x) && x?.key === 'Backspace');
+    const free = i >= 1 && freeOnAltGr(rows[bsRow][i - 1]);
+    try { kb.m_keyboardDiv?.ownerDocument?.documentElement.classList.toggle('vrkbd-del-hint', free); } catch { /* no document */ }
+    const altGr = active(kb.state?.toggleStates?.AltGr);
+    if (!(altGr || kb.__vrkbdDelHold)) return rows;
     if (altGr) rows = rows.map((row) => row.map(keepSize));
-    let done = false;
-    return rows.map((row) => {
-      const i = done ? -1 : row.findIndex((x) => !Array.isArray(x) && x?.key === 'Backspace');
-      if (i < 0) return row;
-      done = true;
-      if (i < 1 || !freeOnAltGr(row[i - 1])) return row;
-      return [...row.slice(0, i - 1), { key: DEL, label: delLabel(), type: row[i].type }, ...row.slice(i)];
-    });
+    if (!free) return rows;
+    const row = rows[bsRow];
+    rows = [...rows];
+    rows[bsRow] = [...row.slice(0, i - 1), { key: DEL, label: delLabel(), type: row[i].type }, ...row.slice(i)];
+    return rows;
   };
   window.__vrkbdLayouts ??= new Set();             // for unpatch.js, incl. layouts disabled since
   for (const l of [...(Layouts.enabledLayouts() || []), Layouts.currentLayout()]) {
@@ -207,6 +212,12 @@
     `[data-key="${DEL}"] { width: 0 !important; flex-grow: 1 !important; }`,
     `[data-key="${DEL}"] > div { justify-content: center !important; text-align: center !important; }`,
     `[data-key="${DEL}"] > div > span { margin: 0 !important; }`,
+    // Delete hint on the free key without AltGr: the arrow hints' size, on
+    // the baseline of Steam's AltGr hints (e.g. } on 0: right/bottom 4px,
+    // 9px, line-height normal; 1px more for 7px's shorter descent).
+    `.vrkbd-del-hint [role="gridcell"]:has(+ [role="gridcell"] > [data-key="Backspace"]) > [data-key]:not([data-key="${DEL}"]) > div::after {` +
+      ` content: ${JSON.stringify(delLabel())}; position: absolute; right: 4px; bottom: 5px; font-size: 7px; line-height: normal;` +
+      ' opacity: 0.45; pointer-events: none; }',
   ].join('\n');
 
   // ---- key handling ----------------------------------------------------------

modules/steam-keyboard-patch/unpatch.js

@@ -26,7 +26,10 @@
     if (refs?.currentLayout) inst.setState({ standardLayout: refs.currentLayout() });
     inst.forceUpdate();
   }
-  for (const p of g_PopupManager.GetPopups?.() || []) p.window?.document.getElementById('vrkbd-style')?.remove();
+  for (const p of g_PopupManager.GetPopups?.() || []) {
+    p.window?.document.getElementById('vrkbd-style')?.remove();
+    p.window?.document.documentElement.classList.remove('vrkbd-del-hint');
+  }
   for (const k of ['__vrkbdHoldTimer', '__vrkbdHeld', '__vrkbdInst', '__vrkbdProto', '__vrkbdLayouts', '__vrkbdRefs', '__vrkbdRendering']) delete window[k];
   return 'unpatched';
 })()