Fix GUI close: Use JUCE custom title bar (not native) + force app activation via ObjC runtime

Source/Helper/HelperPluginHost.cpp

@@ -4,15 +4,33 @@
 #include <pthread.h>
 #include <sched.h>
 
-// Custom window that hides when X is clicked
+#if JUCE_MAC
+#include <objc/objc.h>
+#include <objc/message.h>
+#endif
+
+// Force helper process to become a proper GUI app on macOS
+static void makeGuiProcess()
+{
+#if JUCE_MAC
+    // [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular]
+    id nsApp = ((id(*)(id, SEL))objc_msgSend)((id)objc_getClass("NSApplication"),
+                                               sel_registerName("sharedApplication"));
+    ((void(*)(id, SEL, long))objc_msgSend)(nsApp, sel_registerName("setActivationPolicy:"), 0); // 0 = Regular
+    ((void(*)(id, SEL, int))objc_msgSend)(nsApp, sel_registerName("activateIgnoringOtherApps:"), 1);
+#endif
+}
+
+// Custom window with working close button
 class PluginGuiWindow : public juce::DocumentWindow
 {
 public:
     PluginGuiWindow(const juce::String& name)
-        : DocumentWindow(name, juce::Colour(0xff1a1a2e),
-                         DocumentWindow::allButtons)
+        : DocumentWindow(name, juce::Colour(0xff1a1a2e), DocumentWindow::allButtons, true)
     {
-        setUsingNativeTitleBar(true);
+        // Use JUCE's own title bar — works regardless of macOS activation policy
+        setUsingNativeTitleBar(false);
+        setTitleBarHeight(28);
     }
 
     void closeButtonPressed() override
@@ -248,8 +266,8 @@ void HelperPluginHost::showGui()
     {
         if (!plugin) return;
 
-        // Make this process a foreground app so window buttons work on macOS
-        juce::Process::makeForegroundProcess();
+        // Activate as GUI process (macOS requires this for window interaction)
+        makeGuiProcess();
 
         // If window exists but hidden, just show it
         if (guiWindow)
@@ -265,7 +283,7 @@ void HelperPluginHost::showGui()
         guiWindow = std::make_unique<PluginGuiWindow>(plugin->getName());
         guiWindow->setContentOwned(editor, true);
         guiWindow->setResizable(true, true);
-        guiWindow->centreWithSize(editor->getWidth(), editor->getHeight());
+        guiWindow->centreWithSize(editor->getWidth(), editor->getHeight() + 28); // +28 for title bar
         guiWindow->setVisible(true);
         guiWindow->toFront(true);
     });