Dialogs stay with the program when another one is in front

apps/MasterpieceApp/Main.cpp

@@ -406,6 +406,7 @@ class MasterpieceApp : public juce::JUCEApplication {
     // language comes first.
     proc_->applyChosenLanguage();
     mp::ui::installTouchLook();
+    mp::ui::keepFileDialogsWithProgram();
     mp::ui::restoreLinkedDocuments();
     win_ = std::make_unique<DocWindow>(*proc_, *devices_);
     win_->setVisible(true);

src/mp_audio/CMakeLists.txt

@@ -78,6 +78,9 @@ endif()
 # iPhone and iPad: picked documents read in place (#197).
 if(CMAKE_SYSTEM_NAME STREQUAL "iOS")
   target_sources(mp_audio PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../mp_ui/IosAccess.mm)
+elseif(APPLE)
+  # macOS: the file dialogs stay with the program (#492).
+  target_sources(mp_audio PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../mp_ui/MacWindows.mm)
 endif()
 target_include_directories(mp_audio PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/..)
 target_compile_features(mp_audio PUBLIC cxx_std_20)

src/mp_ui/MacWindows.mm

@@ -0,0 +1,33 @@
+// macOS: the file dialogs stay with the program (#492).
+//
+// JUCE raises an open or save panel to the modal-panel level, above every
+// normal window, and the panel stayed above other programs' windows once the
+// player went to one. Each panel hides when the program leaves the front and
+// comes back with it, as the Recorder and Combinations windows do. One
+// observer, for the application's lifetime: a panel is seen as it takes the
+// keyboard.
+
+#include "Mobile.h"
+
+#if JUCE_MAC
+ #import <AppKit/AppKit.h>
+
+namespace mp::ui {
+
+void keepFileDialogsWithProgram() {
+  static bool installed = false;
+  if (installed) return;
+  installed = true;
+  [[NSNotificationCenter defaultCenter] addObserverForName:NSWindowDidBecomeKeyNotification
+                                                    object:nil
+                                                     queue:nil
+                                                usingBlock:^(NSNotification* note) {
+                                                  id window = note.object;
+                                                  if ([window isKindOfClass:[NSSavePanel class]])
+                                                    [(NSSavePanel*)window setHidesOnDeactivate:YES];
+                                                }];
+}
+
+}  // namespace mp::ui
+
+#endif

src/mp_ui/Mobile.cpp

@@ -519,6 +519,31 @@ class SizeKeeper : public juce::ComponentListener {
 private:
   juce::String kind_;
 };
+
+// JUCE makes a new dialog always on top whenever another of the program's
+// windows is, and the Recorder and Combinations windows are while the
+// program is in front: such a dialog then stayed above every other
+// program's windows (#492). It follows the program in and out of the front,
+// as those windows do. Owned by nobody but itself: it goes with the dialog.
+class FrontFollower : public juce::ComponentListener, private juce::Timer {
+public:
+  explicit FrontFollower(juce::Component& dialog) : dialog_(&dialog) {
+    dialog.addComponentListener(this);
+    startTimer(250);
+  }
+  void componentBeingDeleted(juce::Component& c) override {
+    stopTimer();
+    c.removeComponentListener(this);
+    delete this;
+  }
+
+private:
+  void timerCallback() override {
+    const bool front = juce::Process::isForegroundProcess();
+    if (dialog_ != nullptr && dialog_->isAlwaysOnTop() != front) dialog_->setAlwaysOnTop(front);
+  }
+  juce::Component::SafePointer<juce::Component> dialog_;
+};
 }  // namespace
 
 juce::DialogWindow* launchDialog(juce::DialogWindow::LaunchOptions& options) {
@@ -548,6 +573,7 @@ juce::DialogWindow* launchDialog(juce::DialogWindow::LaunchOptions& options) {
     }
     dialog->addComponentListener(new SizeKeeper(kind));
   }
+  if (kLiveOnTop && !kMobile && dialog->isAlwaysOnTop()) new FrontFollower(*dialog);
   return dialog;
 }
 

src/mp_ui/Mobile.h

@@ -69,6 +69,15 @@ constexpr bool kLiveOnTop = true;
 // screen on a phone or tablet. Every dialog opens through here.
 juce::DialogWindow* launchDialog(juce::DialogWindow::LaunchOptions& options);
 
+// macOS: an open or save panel hides while another program is in front, and
+// comes back with this one (#492; MacWindows.mm). The application calls it
+// once at startup; a plug-in leaves the host's panels alone. Nothing elsewhere.
+#if JUCE_MAC
+void keepFileDialogsWithProgram();
+#else
+inline void keepFileDialogsWithProgram() {}
+#endif
+
 // Closes the front-most window other than `mainWindow`, as its own close
 // button would: Android's back button. False when there was none, so the
 // system's own back behaviour applies. A window whose properties set