Shortcuts: holding a tool's single-key shortcut uses the tool until the key is let go

Holding a single-key tool shortcut becomes temporary: releasing it
returns to the previous tool (a quick tap still switches for good).
With the Pen chosen, holding S chooses Scale; letting go of S after
0.25 s or more, or after Scale was used while S was down, chooses the
Pen again. A press shorter than 0.25 s, with nothing done in between,
keeps Scale chosen as before. The 0.25 s threshold is VectorCraft's own
value. A Cmd/Ctrl click, which the selection tool takes, does not count
as using Scale. A drag of the Hand, Zoom or Rotate View tool chosen
this way counts as using it.

A key let go during a drag, with the pointer button held or with a
dialog open, goes back once that ends. A key let go while the tool
waits for its next click (the Dimension tool after its first point)
goes back once the tool finishes or is canceled. With S held from the
Pen and then V held, letting go of V returns to Scale, and letting go
of S then returns to the Pen. Choosing a tool on the toolbar or from a
menu while the key is down, the held tool included, ends the hold and
keeps that tool, and so does the window losing the keyboard.
While the preference is on, the key's repeats do not choose the tool
again.

The new General preference Hold a Tool Shortcut to Use the Tool
Temporarily (`holdToolKeys`, on by default) turns the behavior off.
With it off, every press and every repeat chooses the tool, as before.
Its label has a row in every catalog.

Docs: docs/mcp.md, docs/target-app-parity.md.

docs/mcp.md

@@ -3637,7 +3637,11 @@ control channel's `ui.drag` scrubs), `showHomeScreen` (on by default: the Home s
 off, an empty window, and the Home button or `app.home` still shows the screen), `autoCollapseIconPanels` (off by
 default: on, a click away from a panel popped out of the icon column puts it away), `displayPrintSize` (off by
 default: View › Actual Size / `view.actualSize` is one document point per screen point; on, one document inch fills
-96 screen points, an inch at the system's reference density whatever the display scaling). `highlightAlternateGlyphs` (off by default: on, the canvas paints a pink cell behind glyphs OpenType features
+96 screen points, an inch at the system's reference density whatever the display scaling). The tool shortcut
+preference `holdToolKeys` also needs the desktop app. It is on by default: a single-key tool shortcut held for 0.25 s
+or more, or held while its tool is used, chooses the tool until the key is let go and then returns to the tool active
+before, after any drag in progress; a quicker press chooses the tool for good. With it off, every press and every key
+repeat chooses the tool. `highlightAlternateGlyphs` (off by default: on, the canvas paints a pink cell behind glyphs OpenType features
 substituted — ligatures, contextual forms — on screen; Document Setup's Highlight Substituted Glyphs stays
 separate). `highlightSubstitutedFonts` (on by default: the canvas paints pink behind text drawn in a substitute for a
 missing font, in every document). `blackOnScreen`

docs/target-app-parity.md

@@ -876,7 +876,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
     Composition's leading-space reduction stays along the line when a character rotates. An opening bracket trimmed by Line-end Punctuation Half Width Mojikumi keeps that placement under Character Rotation; its turning point follows the composition adjustment, and removing the rotation keeps the trim. Scores and estimates are unchanged.
     A character rotated near or at a quarter turn follows a Touch Type drag across its line as well as along it: baseline shift moves a character up from its line at any rotation, and the character turns about its shifted pen position.
     Right-to-left characters can also move along their line when a preceding logical character is on that line. Positive `text.touchType` `dx` follows reading order, toward the left in horizontal right-to-left text; the first logical character still moves only up and down. These direction rules are VectorCraft's choices; the public Touch Type page describes moving a character without specifying this case. Scores and estimates are unchanged.
-  - **Temporary tools:** Cmd with any other tool drags with the selection tool used last (Selection, Direct Selection or Group Selection). Held Space pans and Cmd+Space zooms (Cmd+Alt+Space out) whatever the tool.
+  - **Temporary tools:** Cmd with any other tool drags with the selection tool used last (Selection, Direct Selection or Group Selection). Held Space pans and Cmd+Space zooms (Cmd+Alt+Space out) whatever the tool. A single-key tool shortcut held for 0.25 s or more, or held while its tool is used, chooses that tool only until the key is let go, and the tool active before comes back (after a drag in progress ends); a quicker press chooses the tool for good. This is VectorCraft's own rule and its own threshold, and General › Hold a Tool Shortcut to Use the Tool Temporarily (`holdToolKeys`, on by default) turns it off.
     Space held while the Zoom tool drags a marquee moves the marquee and keeps its size ([Default keyboard shortcuts](https://web.archive.org/web/20260726060015/https://helpx.adobe.com/illustrator/using/default-keyboard-shortcuts.html)). When Space is let go, the drag sizes the marquee again from where it moved to.
     A Space+Shift drag rotates the view whatever the tool, as a Rotate View tool drag does, and Shift does not round the angle to 15°.
   - **Swatches panel clicks:** Ctrl/Cmd-clicking New Swatch makes a spot color, and Ctrl/Cmd+Shift-clicking it makes a global process color.