Attempt to make modifier key changes take affect when the dialogue closes. This means you don't have to restart Fenrir to apply them.

internal/terminal/native.c

@@ -175,7 +175,7 @@ int terminal_key(VTerm *vt, const TerminalEvent *event, char *bytes, int size) {
     return length;
 }
 
-struct TerminalX { Display *display; Window window; unsigned int numlock; int grabbed; XIM im; XIC ic; int scriptKeys[KEY_MAX+1]; int scriptKeyCount; };
+struct TerminalX { Display *display; Window window; unsigned int numlock; int grabbed; XIM im; XIC ic; int scriptKeys[KEY_MAX+1]; int scriptKeyCount; unsigned char grabbedKeys[256]; };
 static int x_error;
 static int trap_error(Display *display, XErrorEvent *event) {
     (void)display;
@@ -206,8 +206,7 @@ static void observe_windows(TerminalX *x, Window window, int depth, int *remaini
     }
     if (children) XFree(children);
 }
-static void install_grabs(TerminalX *x) {
-    Window window = x->window;
+static void collect_grabs(TerminalX *x, const int *keys, int count, unsigned char wanted[256]) {
     x->numlock = 0;
     XModifierKeymap *modifiers = XGetModifierMapping(x->display);
     KeyCode numlock = XKeysymToKeycode(x->display, XK_Num_Lock);
@@ -218,14 +217,14 @@ static void install_grabs(TerminalX *x) {
                     x->numlock |= 1u << mask;
         XFreeModifiermap(modifiers);
     }
-    KeySym keys[] = {XK_Insert,
+    KeySym fixedKeys[] = {XK_Insert,
         XK_KP_Insert, XK_KP_End, XK_KP_Down, XK_KP_Page_Down, XK_KP_Left,
         XK_KP_Begin, XK_KP_Right, XK_KP_Home, XK_KP_Up, XK_KP_Page_Up,
         XK_KP_Delete, XK_KP_Enter, XK_KP_Add, XK_KP_Subtract, XK_KP_Divide,
         XK_Control_L, XK_Control_R};
-    for (unsigned int i=0; i<sizeof(keys)/sizeof(keys[0]); i++) {
-        KeyCode code = XKeysymToKeycode(x->display, keys[i]);
-        if (code) XGrabKey(x->display, code, AnyModifier, window, False, GrabModeAsync, GrabModeSync);
+    for (unsigned int i=0; i<sizeof(fixedKeys)/sizeof(fixedKeys[0]); i++) {
+        KeyCode code = XKeysymToKeycode(x->display, fixedKeys[i]);
+        if (code) wanted[code] = 1;
     }
     // Script modifiers may be any Linux key, not just Compose. Resolve through
     // the same symbol translation as event routing instead of assuming that
@@ -235,14 +234,63 @@ static void install_grabs(TerminalX *x) {
     for (int code=first; code<=last; code++) {
         KeySym symbol = XkbKeycodeToKeysym(x->display, code, 0, 0);
         int key = terminal_key_code(symbol, code);
-        for (int i=0; i<x->scriptKeyCount; i++) {
-            if (key == x->scriptKeys[i]) {
-                XGrabKey(x->display, code, AnyModifier, window, False, GrabModeAsync, GrabModeSync);
+        for (int i=0; i<count; i++) {
+            if (key == keys[i]) {
+                wanted[code] = 1;
                 break;
             }
         }
     }
 }
+static int replace_grabs(TerminalX *x, const int *keys, int count, int idleOnly) {
+    if (count < 0 || count > KEY_MAX+1) return -EINVAL;
+    // Freeze other clients only for the bounded grab transaction. This closes
+    // the gap between the idle check, adding grabs and switching key sets.
+    XGrabServer(x->display);
+    XSync(x->display, False);
+    if (idleOnly) {
+        char down[32];
+        XQueryKeymap(x->display, down);
+        int busy = XPending(x->display) != 0;
+        for (int i=0; i<32; i++) busy |= down[i] != 0;
+        if (busy) { XUngrabServer(x->display); XFlush(x->display); return 1; }
+    }
+    unsigned char wanted[256] = {0};
+    XErrorHandler previous = begin_trap(x->display);
+    collect_grabs(x, keys, count, wanted);
+    for (int code=0; code<256; code++) {
+        if (wanted[code] && !x->grabbedKeys[code])
+            XGrabKey(x->display, code, AnyModifier, x->window, False, GrabModeAsync, GrabModeSync);
+    }
+    int error = end_trap(x->display, previous);
+    if (error) {
+        previous = begin_trap(x->display);
+        for (int code=0; code<256; code++) {
+            if (wanted[code] && !x->grabbedKeys[code])
+                XUngrabKey(x->display, code, AnyModifier, x->window);
+        }
+        end_trap(x->display, previous);
+    } else {
+        for (int code=0; code<256; code++) {
+            if (x->grabbedKeys[code] && !wanted[code])
+                XUngrabKey(x->display, code, AnyModifier, x->window);
+        }
+        memcpy(x->grabbedKeys, wanted, sizeof(wanted));
+        x->scriptKeyCount = count;
+        for (int i=0; i<count; i++) x->scriptKeys[i] = keys[i];
+    }
+    XUngrabServer(x->display);
+    XSync(x->display, False);
+    return error ? -error : 0;
+}
+static void install_grabs(TerminalX *x) {
+    unsigned char wanted[256] = {0};
+    collect_grabs(x, x->scriptKeys, x->scriptKeyCount, wanted);
+    for (int code=0; code<256; code++) {
+        if (wanted[code]) XGrabKey(x->display, code, AnyModifier, x->window, False, GrabModeAsync, GrabModeSync);
+    }
+    memcpy(x->grabbedKeys, wanted, sizeof(wanted));
+}
 int terminal_x_caps_lock(TerminalX *x, int enabled) {
     if (!XkbLockModifiers(x->display, XkbUseCoreKbd, LockMask, enabled ? LockMask : 0)) return -EIO;
     XSync(x->display, False);
@@ -254,13 +302,10 @@ int terminal_x_toggle_caps(TerminalX *x) {
     return terminal_x_caps_lock(x, !(state.locked_mods & LockMask));
 }
 int terminal_x_script_keys(TerminalX *x, const int *keys, int count) {
-    if (count < 0 || count > KEY_MAX+1) return -EINVAL;
-    XErrorHandler previous = begin_trap(x->display);
-    x->scriptKeyCount = count;
-    for (int i=0; i<count; i++) x->scriptKeys[i] = keys[i];
-    install_grabs(x);
-    int error = end_trap(x->display, previous);
-    return error ? -error : 0;
+    return replace_grabs(x, keys, count, 0);
+}
+int terminal_x_update_keys(TerminalX *x, const int *keys, int count) {
+    return replace_grabs(x, keys, count, 1);
 }
 TerminalX *terminal_x_open(unsigned long window, int *error) {
     TerminalX *x = calloc(1, sizeof(*x));