[262] [settings] IJ-CR-210317 IJPL-244826 Disable non-modal settings in CLion Nova and Rider

Migrated control of non-modal settings dialogs to a new Extension Point:
com.intellij.nonModalSettingsPolicy. This resolves a non-deterministic
service override conflict for ShowSettingsUtil between Code With Me
(BackendShowSettingsUtil) and Rider/Radler (RiderShowSettingsUtilImpl):
depending on plugin loading order, BackendShowSettingsUtil could win,
causing CLion Nova and Rider to fall back to the default platform
behavior (non-modal settings enabled by default)

By using an Extension Point with "Modal Wins" aggregation logic:
- Competition for the ShowSettingsUtil service is eliminated
- If any registered policy extension disables non-modal settings, the
  IDE respects that choice regardless of plugin loading order
- A single RiderNonModalSettingsPolicy registered in
  intellij.rider.rdclient.languages covers both Rider and CLion Nova
  across all deployment tiers (monolith, backend, thin-client)

Key changes:
- Defined com.intellij.nonModalSettingsPolicy EP in platform-api with
  aggregation logic in the NonModalSettingsPolicy companion object
- ShowSettingsUtilImpl delegates isNonModalSettingsEnabled() to the EP
- Removed ShowSettingsUtil service overrides from RiderShowSettingsUtilImpl
  and CppFrontendShowSettingsUtilImpl; deleted CppFrontendShowSettingsUtilImpl
- Added NonModalSettingsAdvancedSettingService (platform-impl) as a
  minimal bridge for the Advanced Settings framework visibility check

(cherry picked from commit 2d0edc141be4804163cdda84f6898d31c2168fdd)

GitOrigin-RevId: 8289a8c0879c4c33530244e597da05a8572ac218

platform/platform-api/src/com/intellij/openapi/options/NonModalSettingsPolicy.kt

@@ -0,0 +1,54 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.openapi.options
+
+import com.intellij.openapi.extensions.ExtensionPointName
+import org.jetbrains.annotations.ApiStatus
+
+/**
+ * Controls whether a non-modal settings dialog is available
+ *
+ * Products that don't support non-modal settings (e.g. Rider, CLion Nova)
+ * can register an extension to disable the feature and hide the corresponding Advanced Setting.
+ *
+ * This policy is intentionally separated from [ShowSettingsUtil] to avoid
+ * service-override ordering issues when multiple plugins override [ShowSettingsUtil]
+ * (e.g. CWM's `BackendShowSettingsUtil` and Rider's `RiderShowSettingsUtilImpl`).
+ */
+@ApiStatus.Internal
+interface NonModalSettingsPolicy {
+  companion object {
+    @ApiStatus.Internal
+    val EP_NAME: ExtensionPointName<NonModalSettingsPolicy> = ExtensionPointName.create("com.intellij.nonModalSettingsPolicy")
+
+    /**
+     * Aggregated check for all registered [NonModalSettingsPolicy] extensions.
+     */
+    fun isNonModalSettingsEnabledByAllPolicies(): Boolean {
+      if (EP_NAME.extensionList.any { !it.isNonModalSettingsEnabled() }) {
+        return false
+      }
+      return System.getProperty("ide.ui.non.modal.settings.window")?.toBoolean()
+             ?: com.intellij.openapi.options.advanced.AdvancedSettings.getBoolean("ide.ui.non.modal.settings.window")
+    }
+
+    /**
+     * Aggregated check for all registered [NonModalSettingsPolicy] extensions.
+     */
+    fun isNonModalSettingsWindowSettingVisibleInAllPolicies(): Boolean {
+      return EP_NAME.extensionList.all { it.isNonModalSettingsWindowSettingVisible() }
+    }
+  }
+
+  /**
+   * Whether the non-modal settings window feature is enabled for this product.
+   * When `false`, settings are always shown in a modal dialog.
+   */
+  fun isNonModalSettingsEnabled(): Boolean
+
+  /**
+   * Controls the visibility of the "Show Settings in non-modal window" option in Advanced Settings.
+   * When `false`, the Advanced Setting is hidden (along with non-modal settings being disabled).
+   */
+  fun isNonModalSettingsWindowSettingVisible(): Boolean
+}
+

platform/platform-impl/src/com/intellij/ide/actions/ShowSettingsUtilImpl.kt

@@ -15,9 +15,9 @@ import com.intellij.openapi.diagnostic.getOrLogException
 import com.intellij.openapi.diagnostic.logger
 import com.intellij.openapi.options.Configurable
 import com.intellij.openapi.options.ConfigurableGroup
+import com.intellij.openapi.options.NonModalSettingsPolicy
 import com.intellij.openapi.options.ShowSettingsUtil
 import com.intellij.openapi.options.TabbedConfigurable
-import com.intellij.openapi.options.advanced.AdvancedSettings
 import com.intellij.openapi.options.ex.ConfigurableExtensionPointUtil
 import com.intellij.openapi.options.ex.ConfigurableVisitor
 import com.intellij.openapi.options.ex.ConfigurableWrapper
@@ -130,17 +130,11 @@ open class ShowSettingsUtilImpl : ShowSettingsUtil() {
     }
   }
 
-  @ApiStatus.Internal
-  protected open fun isNonModalSettingsEnabled(): Boolean = useNonModalSettingsWindow()
-
-  @ApiStatus.Internal
-  open fun isNonModalSettingsWindowVisible(): Boolean = true
-
   @ApiStatus.Internal
   protected open fun doShow(project: Project?, groups: List<ConfigurableGroup>, toSelect: Configurable?, filter: String?) {
     val isModal = !(project != null &&
                     project != ProjectManager.getInstance().defaultProject &&
-                    isNonModalSettingsEnabled() &&
+                    NonModalSettingsPolicy.isNonModalSettingsEnabledByAllPolicies() &&
                     ModalityState.current() == ModalityState.nonModal())
 
     val filteredGroups = filterEmptyGroups(groups)
@@ -163,8 +157,8 @@ open class ShowSettingsUtilImpl : ShowSettingsUtil() {
     // We want to ensure that clients don’t simply replace one API with another,
     // but actually rework the invocation to be performed not in EDT.
     ThreadingAssertions.assertBackgroundThread()
-
-    val isModal = project.isDefault || !isNonModalSettingsEnabled()
+ 
+    val isModal = project.isDefault || !NonModalSettingsPolicy.isNonModalSettingsEnabledByAllPolicies()
     withContext(Dispatchers.EDT) {
       if (!isModal) {
         SettingsNonModalDialogFactory.getInstance().show(project, filterEmptyGroups(groups), null, null)
@@ -367,11 +361,6 @@ private fun <T : Configurable> editConfigurable(
   return editor.showAndGet()
 }
 
-private fun useNonModalSettingsWindow(): Boolean {
-  return System.getProperty("ide.ui.non.modal.settings.window")?.toBoolean()
-         ?: AdvancedSettings.getBoolean("ide.ui.non.modal.settings.window")
-}
-
 internal fun scheduleDoShowSettingsDialogWithACheckThatProjectIsInitialized(project: Project) {
   project.service<CoreUiCoroutineScopeHolder>().coroutineScope.launch {
     launch {

platform/platform-impl/src/com/intellij/openapi/options/NonModalSettingsAdvancedSettingService.kt

@@ -0,0 +1,18 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.openapi.options
+
+import org.jetbrains.annotations.ApiStatus
+
+/**
+ * Service used solely for the `ide.ui.non.modal.settings.window` Advanced Setting visibility check.
+ *
+ * The Advanced Settings framework with `property="nonModalSettingsWindow"` calls
+ * `isNonModalSettingsWindowVisible()` on this service instance to decide whether the setting
+ * should appear in the Advanced Settings UI.
+ *
+ * Actual policy aggregation is delegated to [NonModalSettingsPolicy.isNonModalSettingsWindowSettingVisibleInAllPolicies].
+ */
+@ApiStatus.Internal
+class NonModalSettingsAdvancedSettingService {
+  fun isNonModalSettingsWindowVisible(): Boolean = NonModalSettingsPolicy.isNonModalSettingsWindowSettingVisibleInAllPolicies()
+}

platform/platform-resources/src/META-INF/PlatformExtensionPoints.xml

@@ -109,6 +109,8 @@
                     area="IDEA_PROJECT"
                     dynamic="true"/>
 
+    <extensionPoint name="nonModalSettingsPolicy" interface="com.intellij.openapi.options.NonModalSettingsPolicy" dynamic="true"/>
+
     <extensionPoint name="undoProvider" interface="com.intellij.openapi.command.impl.UndoProvider" dynamic="true"/>
     <extensionPoint name="projectUndoProvider" interface="com.intellij.openapi.command.impl.UndoProvider"
                     area="IDEA_PROJECT" dynamic="true"/>

platform/platform-resources/src/META-INF/PlatformExtensions.xml

@@ -1802,8 +1802,9 @@ The refresh itself is toggled by (Preferences | Appearance & Behavior | Syst
     <advancedSetting id="search.everywhere.show.results.notification" default="true" groupKey="group.advanced.settings.se"/>
     <advancedSetting id="search.everywhere.contributors.wait.timeout" default="2000" groupKey="group.advanced.settings.se"/>
     <advancedSetting id="search.everywhere.recent.at.top" default="true" groupKey="group.advanced.settings.se"/>
+    <applicationService serviceImplementation="com.intellij.openapi.options.NonModalSettingsAdvancedSettingService"/>
     <advancedSetting id="ide.ui.non.modal.settings.window" default="true" groupKey="group.advanced.settings.ui"
-                     service="com.intellij.openapi.options.ShowSettingsUtil" property="nonModalSettingsWindow"/>
+                     service="com.intellij.openapi.options.NonModalSettingsAdvancedSettingService" property="nonModalSettingsWindow"/>
 
     <backgroundPostStartupActivity implementation="com.intellij.ide.plugins.DependencyFeatureCollector"/>
     <projectService serviceInterface="com.intellij.presentation.FilePresentationService"