Send typing to the panel clicked last

An ungrabbed keyboard reached both sides at once: gamescope, which in VR
reads every input device itself (the SteamOS build's InputStealer), typed
into its focused app, and ft-screens typed into the desktop. Space in the
desktop paused Spotify on the dashboard, including every space frame-voice
dictated. And while the SteamVR dashboard was open, the desktop got no
keys at all.

Typing now follows the last click. ft-screens sees clicks on its own
screens; the pointer helper reports the panel under the dot on each mouse
press, so a click on any other panel sends typing to Steam. While typing
goes to the desktop and the screens are showing, ft-screens tells the
relay every second, and the relay grabs pass-through keyboards. A grab
waits until no key is down, and the relay lets go if ft-screens stops
reporting. Controller clicks on other panels aren't visible to overlay
apps, so they don't move typing (noted in the README).

A program that reads every keyboard for a hotkey loses a grabbed one.
Repeating the keys on another input device doesn't work, since gamescope
reads that too, so with SHARE_KEYS=1 the relay sends them to
@frametop_keys as datagrams with the device name. It's off by default:
any local process that binds that name first would get every key typed
into the desktop.

The docs now say gamescope reads keyboards and the headset's buttons
itself; they said SteamVR passed keys on to it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/design.md

@@ -100,7 +100,9 @@ SteamVR opens every input device only when it starts. When a Bluetooth mouse sle
 
 Keyboards aren't grabbed by default, because a grabbed keyboard's keys went into a virtual keyboard nothing typed from; the relay forwards them to ft-screens instead.
 
-Volume keys must never reach gamescope. With the openvr backend, gamescope sends volume up and down to Steam by moving keyboard focus to Steam for the key and then back to the previously focused surface. When nothing had focus, the one it moves back to is null, and wlroots aborts on a null focus surface (`wlr_seat_keyboard_notify_enter: Assertion 'surface' failed`), which ends the whole VR session. Keyboard focus is often empty while you work in VR, so one press of the headset's volume button could take everything down. SteamVR reads the headset's buttons itself and passes keys on to gamescope, so the relay has to stop volume keys before SteamVR sees them. Grabbing `gpio-keys` would also take the headset's click button, so the relay remaps the volume entries in each device's keymap (`EVIOCSKEYCODE`) and handles the stand-in codes itself. That fix covers every device at once, including keyboards that aren't grabbed.
+An ungrabbed keyboard reaches both sides at once. In VR, gamescope reads every input device itself (the SteamOS build's `InputStealer`, libinput with udev hotplug, so new devices too) and types into its focused app, and ft-screens types the same keys into the desktop. So Space in the desktop also paused Spotify on the dashboard. Typing now follows the last click. ft-screens sees clicks on its own screens, from the mouse or a controller. A click anywhere else is only visible for the mouse: overlay apps get SteamVR's `OverlayFocusChanged` (which panel the laser is on) but no controller button events, so the pointer helper reports the panel under the dot on each left press. ft-screens tells the relay where typing goes every second, from an unbound socket so the relay's replies can't loop back into its control socket, and the relay grabs pass-through keyboards while it's the desktop. A grab waits until the keyboard has no key down, so no key stays held on either side, and the relay lets go if ft-screens stops reporting. A program that reads every keyboard for a hotkey (a dictation tool, say) loses a grabbed keyboard. Repeating the keys on another input device doesn't work: gamescope reads that device too, whether it's the relay's virtual keyboard or one created later, and every Space, typed or dictated, paused Spotify again. So with `SHARE_KEYS=1` the relay sends a grabbed keyboard's keys to `@frametop_keys` as datagrams (`key <code> <value> <device name>`). It's off by default, because the relay can't tell who is listening: abstract sockets have no permissions, and any local process that binds the name first gets every key typed into the desktop, passwords included. A listener should accept only its own user (`SO_PASSCRED`) and skip any keyboard of its own that the relay grabs too.
+
+Volume keys must never reach gamescope. With the openvr backend, gamescope sends volume up and down to Steam by moving keyboard focus to Steam for the key and then back to the previously focused surface. When nothing had focus, the one it moves back to is null, and wlroots aborts on a null focus surface (`wlr_seat_keyboard_notify_enter: Assertion 'surface' failed`), which ends the whole VR session. Keyboard focus is often empty while you work in VR, so one press of the headset's volume button could take everything down. gamescope reads the headset's buttons and every keyboard itself (`InputStealer`), as do SteamVR's processes, so the relay has to stop volume keys at the device. Grabbing `gpio-keys` would also take the headset's click button, so the relay remaps the volume entries in each device's keymap (`EVIOCSKEYCODE`) and handles the stand-in codes itself. That fix covers every device at once, including keyboards that aren't grabbed.
 
 ## The desktop session
 

docs/reference.md

@@ -51,7 +51,7 @@ In the last three modes the hotkey shows the screens anyway. Two more settings o
 - During VR games, the Always mode hides the screens unless the dashboard is open (the default), or leaves them up.
 - Controllers on the screens. Visible screens can keep SteamVR's laser mouse on, so controllers work them with the dashboard closed, but that also takes the controllers away from a game. By default this is off while a VR game runs, and the 3D mouse or the dashboard works the screens. The other choices are always on, or only with the dashboard open, which also suits flatscreen games since they aren't scene apps.
 
-Input from the lasers reaches KWin through ft-screens' own seat. Keys come from the input relay, from any keyboard it doesn't grab and any key a pointer device passes through, and go to the screen you clicked last, except while the SteamVR dashboard is open.
+Input from the lasers reaches KWin through ft-screens' own seat. Keys come from the input relay, from pass-through keyboards and any key a pointer device passes through. Typing follows your last click: after a click on a screen it goes to the desktop, even with the SteamVR dashboard open, and after a mouse click on any other panel (the dashboard, Steam, an app like Spotify) it goes there instead. While it goes to the desktop, the relay grabs pass-through keyboards so gamescope, which reads every keyboard itself, doesn't type them into the Steam app too. A program that watches every keyboard for a hotkey loses a grabbed one; with `SHARE_KEYS=1` in `~/.config/frametop.conf`, their keys also go to `@frametop_keys` for it. That's off by default, since any local process that binds the name first would get everything typed into the desktop. Hidden screens don't take typing.
 
 ft-screens listens for datagrams on the abstract socket `@ft_screens` and replies to the sender:
 
@@ -69,7 +69,7 @@ SteamVR opens input devices only when it starts. A Bluetooth mouse that sleeps a
 
 It runs as the user service `frametop-input-relay.service`, ordered before `steamvr.service`.
 
-The relay also owns the volume keys, on every device that has them, the headset's buttons included. It changes the volume itself (`wpctl`, 5% a step, repeating while held), and SteamVR never sees a volume key: on devices with a keymap (the headset's `gpio-keys`, USB and Bluetooth keyboards) it remaps just the volume entries to unused codes (`KEY_MACRO29`, `KEY_MACRO30`), so the headset's click button and the other keys still reach SteamVR, and it grabs `pmic_resin`, which has only volume down. The keymaps go back when the relay stops. With `--no-grab` it leaves the volume keys alone.
+The relay also owns the volume keys, on every device that has them, the headset's buttons included. It changes the volume itself (`wpctl`, 5% a step, repeating while held), and nothing else sees a volume key, gamescope and SteamVR included: on devices with a keymap (the headset's `gpio-keys`, USB and Bluetooth keyboards) it remaps just the volume entries to unused codes (`KEY_MACRO29`, `KEY_MACRO30`), so the headset's click button and the other keys still work, and it grabs `pmic_resin`, which has only volume down. The keymaps go back when the relay stops. With `--no-grab` it leaves the volume keys alone.
 
 ```
 desktops.sh relay install     # enable it (starts with the next reboot or SteamVR start)
@@ -104,7 +104,7 @@ The pointer settings are in `~/.config/frametop.conf`: `POINTER_SENSITIVITY`, `P
 
 A Kirigami app with a Python backend, in the Plasma menu under Settings. It runs in the `dev` container and talks to the relay over its control socket, `@frametop_relay`. It has four pages:
 
-- Devices lists every USB and Bluetooth mouse and keyboard, with a light that flashes when the device is used. Each device gets a role: 3D pointer (grabbed, drives the pointer; the default for anything with a mouse), Pass through (not grabbed; the default for keyboards, where a Meta tap toggles the dashboard if `META_DASHBOARD=1` is in `~/.config/frametop.conf`), or Ignore. A device is identified by its Bluetooth address, or its USB ids and name, so all of its input nodes share one role. Forget drops everything saved for a device.
+- Devices lists every USB and Bluetooth mouse and keyboard, with a light that flashes when the device is used. Each device gets a role: 3D pointer (grabbed, drives the pointer; the default for anything with a mouse), Pass through (grabbed only while typing goes to the desktop; the default for keyboards, where a Meta tap toggles the dashboard if `META_DASHBOARD=1` is in `~/.config/frametop.conf`), or Ignore. A device is identified by its Bluetooth address, or its USB ids and name, so all of its input nodes share one role. Forget drops everything saved for a device.
 - Buttons maps a pointer device's buttons. Choose Capture a button, press the button or key, then pick an action: a click, back, scroll, toggle dashboard, recenter, pointer on or off, faster or slower, pass the key through, or nothing. Devices with saved mappings are listed even while they're asleep.
 - Pointer has sliders for the pointer settings, which apply immediately, and a Recenter button.
 - Bluetooth lists paired devices and has Apply Bluetooth fixes, which runs `/etc/steamframe/bt-fixups.sh` through `pkexec`. Pair new devices in Steam.