We need those things after all

dpf/dgl/src/WindowPrivateData.cpp

@@ -560,6 +560,10 @@ void Window::PrivateData::startModal()
     modal.parent->show();
     show();
 
+#ifdef DISTRHO_OS_MAC
+    puglMacOSAddChildWindow(modal.parent->view, view);
+#endif
+
     DGL_DBG("Ok\n");
 }
 
@@ -576,6 +580,10 @@ void Window::PrivateData::stopModal()
     if (modal.parent->modal.child != this)
         return;
 
+#ifdef DISTRHO_OS_MAC
+    puglMacOSRemoveChildWindow(modal.parent->view, view);
+#endif
+
     // stop parent from giving focus to us, so it behaves like normal
     modal.parent->modal.child = nullptr;
 

dpf/dgl/src/pugl.cpp

@@ -407,6 +407,46 @@ void puglMacOSActivateApp()
     [NSApp activateIgnoringOtherApps:YES];
 }
 
+// --------------------------------------------------------------------------------------------------------------------
+// macOS specific, add another view's window as child
+
+PuglStatus
+puglMacOSAddChildWindow(PuglView* const view, PuglView* const child)
+{
+    if (NSWindow* const viewWindow = view->impl->window ? view->impl->window
+                                                        : [view->impl->wrapperView window])
+    {
+        if (NSWindow* const childWindow = child->impl->window ? child->impl->window
+                                                              : [child->impl->wrapperView window])
+        {
+            [viewWindow addChildWindow:childWindow ordered:NSWindowAbove];
+            return PUGL_SUCCESS;
+        }
+    }
+
+    return PUGL_FAILURE;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+// macOS specific, remove another view's window as child
+
+PuglStatus
+puglMacOSRemoveChildWindow(PuglView* const view, PuglView* const child)
+{
+    if (NSWindow* const viewWindow = view->impl->window ? view->impl->window
+                                                        : [view->impl->wrapperView window])
+    {
+        if (NSWindow* const childWindow = child->impl->window ? child->impl->window
+                                                              : [child->impl->wrapperView window])
+        {
+            [viewWindow removeChildWindow:childWindow];
+            return PUGL_SUCCESS;
+        }
+    }
+
+    return PUGL_FAILURE;
+}
+
 // --------------------------------------------------------------------------------------------------------------------
 // macOS specific, setup file browser dialog
 

dpf/dgl/src/pugl.hpp

@@ -100,6 +100,14 @@ puglFallbackOnResize(PuglView* view);
 PUGL_API void
 puglMacOSActivateApp();
 
+// macOS specific, add another view's window as child
+PUGL_API PuglStatus
+puglMacOSAddChildWindow(PuglView* view, PuglView* child);
+
+// macOS specific, remove another view's window as child
+PUGL_API PuglStatus
+puglMacOSRemoveChildWindow(PuglView* view, PuglView* child);
+
 // macOS specific, setup file browser dialog
 typedef void (*openPanelCallback)(PuglView* view, const char* path);
 bool puglMacOSFilePanelOpen(PuglView* view, const char* startDir, const char* title, uint flags, openPanelCallback callback);