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/input/modifiers_linux.go

@@ -149,6 +149,7 @@ func (r *Router) Configure_modifiers(fenrirKeys, scriptKeys []string) error {
 	if err := candidate.Configure_scripts(scriptKeys, nil); err != nil {
 		return err
 	}
+	candidate.scriptBindings = r.scriptBindings
 	*r = candidate
 	return nil
 }

internal/input/modifiers_test.go

@@ -94,3 +94,20 @@ func TestCapsLockScriptModifierKeepsShiftToggle(t *testing.T) {
 		t.Fatal("script chord toggled capitalization", got)
 	}
 }
+
+func TestModifierReconfigurationPreservesInstalledScriptBindings(t *testing.T) {
+	r := desktop_router(t)
+	if err := r.Configure_modifiers([]string{"KEY_INSERT"}, []string{"KEY_COMPOSE"}); err != nil {
+		t.Fatal(err)
+	}
+	if err := r.Configure_scripts([]string{"KEY_COMPOSE"}, []ScriptBinding{{ID: "script:example", Keys: []string{"KEY_SCRIPT", "KEY_U"}}}); err != nil {
+		t.Fatal(err)
+	}
+	if err := r.Configure_modifiers([]string{"KEY_META"}, []string{"KEY_CAPSLOCK"}); err != nil {
+		t.Fatal(err)
+	}
+	r.Key(0, KeyCapsLock, 1, false, false)
+	if got := r.Key(0, 22, 1, false, false); got.Command != "script:example" {
+		t.Fatal("script binding lost", got)
+	}
+}

internal/input/router.go

@@ -134,6 +134,9 @@ func (r *Router) Forwarded(device int) []uint16 {
 	return keys
 }
 
+// Idle reports whether all devices have released their routed keys.
+func (r *Router) Idle() bool { return r.empty() }
+
 // Held reports physical state for one device, including consumed keys whose
 // release has not arrived yet.
 func (r *Router) Held(device int) bool { return len(r.keys[device]) != 0 }