Ssshh!!! Secret flag to force colorful toolbar even when one project is open

(cherry picked from commit 6fe9ebaf6d5b68edb4c9a5e3d10d698479e46e09)

GitOrigin-RevId: 66b4affb93c67eb181baa3a03ef4151e83870ab7

platform/platform-impl/src/com/intellij/ide/ProjectWindowCustomizerService.kt

@@ -12,6 +12,7 @@ import com.intellij.openapi.project.ProjectManager
 import com.intellij.openapi.project.ex.ProjectManagerEx
 import com.intellij.openapi.startup.ProjectActivity
 import com.intellij.openapi.util.Disposer
+import com.intellij.openapi.util.registry.Registry
 import com.intellij.openapi.wm.ex.WindowManagerEx
 import com.intellij.openapi.wm.impl.ProjectFrameHelper
 import com.intellij.ui.GotItTooltip
@@ -50,7 +51,7 @@ class ProjectWindowCustomizerService : Disposable {
   internal fun update(newValue: Boolean) {
     if (newValue != ourSettingsValue) {
       ourSettingsValue = newValue
-      wasGradientPainted = newValue && ProjectManager.getInstance().openProjects.size > 1
+      wasGradientPainted = newValue && conditionToEnable()
       fireUpdate()
     }
   }
@@ -71,12 +72,14 @@ class ProjectWindowCustomizerService : Disposable {
   }
 
   fun enableIfNeeded() {
-    if (ProjectManagerEx.getOpenProjects().size > 1 && !wasGradientPainted) {
+    if (conditionToEnable() && !wasGradientPainted) {
       wasGradientPainted = true
       fireUpdate()
     }
   }
 
+  private fun conditionToEnable() = ProjectManagerEx.getOpenProjects().size > 1 || Registry.`is`("ide.colorful.toolbar.force")
+
   fun addListener(disposable: Disposable, fireFirstTime: Boolean, listener: (Boolean) -> Unit) {
     if (fireFirstTime) {
       listener(isActive())
@@ -92,6 +95,7 @@ class ProjectWindowCustomizerService : Disposable {
   }
 
   fun shouldShowGotIt() = !gotItShown
+
   private fun recordGotItShown() {
     gotItShown = true
   }

platform/util/resources/misc/registry.properties

@@ -2337,5 +2337,9 @@ ide.speed.search.allow.custom.location.description=Allow using SpeedSearchSupply
 ide.log.coroutine.pce=true
 ide.log.coroutine.pce.description=Log PCEs occurring in coroutines. \
   These exceptions are treated as failure by coroutine framework, and should be reported as such.
+
+ide.colorful.toolbar.force=false
+ide.colorful.toolbar.force.description=Show 'Colorful toolbar' even if there is one project open (works only if the feature is enabled). \
+  Reopen project or restart IDE to apply the setting
 # please leave this note as last line
 # TODO please use EP com.intellij.registryKey for plugin/product specific keys