fix GUI VSTi trắng/không load: DPI per-monitor v2 + WS_CLIPCHILDREN + view->onSize() sau attached; restore API manager header/cpp (2596372 xoá nhầm) và deploy exe mới

native_bridge/src/Vst3Instrument.cpp

@@ -555,10 +555,12 @@ bool Vst3Instrument::attachView(void* parentWindowHandle) {
     auto* s = static_cast<Vst3HostState*>(state_);
     if (!s || !s->controller || !parentWindowHandle) return false;
     IPlugView* rawView = nullptr;
+    s->controller->queryInterface(IPlugView::iid, (void**)&rawView);
     FUnknownPtr<IPlugView> view(rawView);
     if (!view) {
         // Mot so plugin khong expose IPlugView tren edit controller; thu component.
         IPlugView* rawViewC = nullptr;
+        s->component->queryInterface(IPlugView::iid, (void**)&rawViewC);
         view = FUnknownPtr<IPlugView>(rawViewC);
     }
     if (!view) {
@@ -566,7 +568,9 @@ bool Vst3Instrument::attachView(void* parentWindowHandle) {
         // JUCE-based plugins (Scaler2) expose the editor only this way.
         view = owned(s->controller->createView(Steinberg::Vst::ViewType::kEditor));
     }
+    if (!view) return false;
     view->setFrame(&s->plugFrame);
+    view->isPlatformTypeSupported(kPlatformTypeHWND);
     tresult ta = view->attached(parentWindowHandle, kPlatformTypeHWND);
     if (ta != kResultOk) return false;
 #ifdef _WIN32
@@ -578,6 +582,10 @@ bool Vst3Instrument::attachView(void* parentWindowHandle) {
         RECT r = { 0, 0, w, h };
         AdjustWindowRect(&r, WS_OVERLAPPEDWINDOW, FALSE);
         SetWindowPos(hwnd, nullptr, 0, 0, r.right - r.left, r.bottom - r.top, SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
+        // Tell the plugin the client size right after attach — some editors
+        // (Skia/OpenGL-based) skip their first paint until onSize arrives,
+        // leaving a blank/white surface.
+        view->onSize(&rect);
     }
 #endif
     s->view = view;