Pointer: ft-screens announces new panels to the helper

The helper now reads SteamVR's list of panels every 20 s instead of every second, so a panel
made in between (a floating window's menu, frametop.float.N.sub.K, or the Frametop keyboard
the first time it opens) couldn't be clicked with the mouse until the next read. ft-screens
now sends "overlay <key>" to @ft_pointer_helper right after it makes one, and the helper adds
it to its list at once (only frametop.* keys). An older helper ignores it.

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

pointer/helper/ft-pointer.cpp

@@ -582,6 +582,17 @@ public:
         for (const auto &e : entries_) keys.push_back(e.key);
         return keys;
     }
+    // A panel just made by another Frametop program (ft-screens: a floating window's menu, the
+    // keyboard): known at once, without waiting for the next read ("overlay <key>").
+    void Add(const std::string &key) {
+        {
+            std::lock_guard<std::mutex> guard(lock_);
+            for (const auto &e : entries_)
+                if (e.key == key) return;
+            entries_.push_back({key, key, true});
+        }
+        ++generation_;
+    }
     // Goes up by one each time the list is read, so the main loop knows to look the keys up again.
     unsigned Generation() const { return generation_; }
     // Answer `to` with {"t":"overlays","list":[{"key","name","visible"}...]} after the next refresh.
@@ -1522,6 +1533,10 @@ int main() {
                 reply(controllerButtons.Status());
                 continue;
             }
+            if (std::strncmp(buf, "overlay ", 8) == 0 && std::strncmp(buf + 8, "frametop.", 9) == 0) {
+                overlays.Add(buf + 8);
+                continue;
+            }
             if (std::strncmp(buf, "overlays", 8) == 0) {
                 overlays.Request(sender, senderLen);  // answered from the list's thread
                 continue;

screens/vr.cpp

@@ -966,6 +966,19 @@ void SendFloat(const std::string &msg) {
         std::printf("to ft-floatd: %s\n", msg.c_str());
 }
 
+// A new panel: the pointer helper reads SteamVR's list of panels only every 20 s, so it's told
+// at once ("overlay <key>"), or the mouse couldn't click a menu until then.
+void AnnounceOverlay(const char *key) {
+    static const int fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
+    sockaddr_un addr{};
+    addr.sun_family = AF_UNIX;
+    const char name[] = "ft_pointer_helper";
+    std::memcpy(addr.sun_path + 1, name, sizeof name - 1);
+    const std::string msg = std::string("overlay ") + key;
+    sendto(fd, msg.data(), msg.size(), MSG_DONTWAIT, reinterpret_cast<sockaddr *>(&addr),
+           socklen_t(offsetof(sockaddr_un, sun_path) + 1 + sizeof name - 1));
+}
+
 // Where a device's ray meets the screen's plane, in the screen's x (right) and y (up),
 // metres from its centre.
 bool RayOnPlane(const Mat &p, const Mat &d, double *x, double *y) {
@@ -1313,6 +1326,7 @@ void SetSub(Screen &s, int index, int k, int x, int y, int w, int h) {
         vr::VROverlay()->SetOverlayFlag(sub.overlay, vr::VROverlayFlags_SendVRDiscreteScrollEvents, true);
         vr::VROverlay()->SetOverlayFlag(sub.overlay, vr::VROverlayFlags_MakeOverlaysInteractiveIfVisible, s.lasers);
         vr::VROverlay()->SetOverlaySortOrder(sub.overlay, 5);
+        AnnounceOverlay(key);
         it = s.subs.emplace(k, sub).first;
         if (s.shown) {
             auto imp = g_imports.find(s.shown);
@@ -1573,7 +1587,7 @@ void UpdateSteamInFront() {
         g_keyboardAside = true;
     } else if (!front && g_keyboardAside) {
         g_keyboardAside = false;
-        keyboard::Show(g_asidePose);
+        if (keyboard::Show(g_asidePose)) AnnounceOverlay("frametop.keyboard");
     }
 }
 
@@ -2020,7 +2034,9 @@ bool ft_vr_keyboard_show(int index) {
         std::printf("keyboard: waiting for Steam to close\n");
         return true;
     }
-    return keyboard::Show(FacingPose(at, head));
+    if (!keyboard::Show(FacingPose(at, head))) return false;
+    AnnounceOverlay("frametop.keyboard");
+    return true;
 }
 
 void ft_vr_keyboard_hide(void) {