VST3 Host: Ensure that plugins open with their top left corner in the right position

This fixes a bug on Windows where plugins that do not implement the
IPlugViewContentScaleSupport interface opened in the AudioPluginHost
with their editors in the very top left corner of the window, rather
than below the window's titlebar.

Examples of plugins with no scaling support, suitable for reproducing
the issue:
- U-He Hive 2.1.1 Rev 12092 x64
- FabFilter Pro-C 1.23 x64

modules/juce_audio_processors/format_types/juce_VST3PluginFormat.cpp

@@ -1450,22 +1450,9 @@ struct VST3PluginWindow : public AudioProcessorEditor,
         }
     }
 
-    void componentMovedOrResized (bool wasMoved, bool wasResized) override
+    void componentMovedOrResized (bool, bool wasResized) override
     {
-        if (recursiveResize || getTopLevelComponent()->getPeer() == nullptr)
-            return;
-
-        ignoreUnused (wasMoved);
-
-       #if JUCE_WINDOWS
-        if (wasMoved)
-        {
-            const auto pos = getPluginWindowTopLeft();
-            setPluginWindowPos ({ pos.x, pos.y, 0, 0 }, SWP_NOSIZE);
-        }
-       #endif
-
-        if (! wasResized)
+        if (recursiveResize || ! wasResized || getTopLevelComponent()->getPeer() == nullptr)
             return;
 
         ViewRect rect;
@@ -1485,8 +1472,7 @@ struct VST3PluginWindow : public AudioProcessorEditor,
             }
 
            #if JUCE_WINDOWS
-            setPluginWindowPos (Rectangle<int> (rect.getWidth(), rect.getHeight())
-                                  .withPosition (getPluginWindowTopLeft()), 0);
+            setPluginWindowPos (rect);
            #else
             embeddedComponent.setBounds (getLocalBounds());
            #endif
@@ -1498,8 +1484,7 @@ struct VST3PluginWindow : public AudioProcessorEditor,
             warnOnFailure (view->getSize (&rect));
 
            #if JUCE_WINDOWS
-            setPluginWindowPos (Rectangle<int> (rect.getWidth(), rect.getHeight())
-                                  .withPosition (getPluginWindowTopLeft()), 0);
+            setPluginWindowPos (rect);
            #else
             resizeWithRect (embeddedComponent, rect, nativeScaleFactor);
            #endif
@@ -1528,13 +1513,10 @@ struct VST3PluginWindow : public AudioProcessorEditor,
 
         nativeScaleFactor = (float) newScaleFactor;
 
-        if (pluginHandle == HandleFormat{})
-            return;
-
-        if (scaleInterface != nullptr)
+        if (pluginHandle != HandleFormat{} && scaleInterface != nullptr)
             scaleInterface->setContentScaleFactor ((Steinberg::IPlugViewContentScaleSupport::ScaleFactor) nativeScaleFactor);
-
-        componentMovedOrResized (true, true);
+        else
+            resizeToFit();
     }
 
     void resizeToFit()
@@ -1586,10 +1568,8 @@ private:
     //==============================================================================
     static void resizeWithRect (Component& comp, const ViewRect& rect, float scaleFactor)
     {
-        comp.setBounds (roundToInt ((float) rect.left / scaleFactor),
-                        roundToInt ((float) rect.top  / scaleFactor),
-                        jmax (10, std::abs (roundToInt ((float) rect.getWidth()  / scaleFactor))),
-                        jmax (10, std::abs (roundToInt ((float) rect.getHeight() / scaleFactor))));
+        comp.setSize (jmax (10, std::abs (roundToInt ((float) rect.getWidth()  / scaleFactor))),
+                      jmax (10, std::abs (roundToInt ((float) rect.getHeight() / scaleFactor))));
     }
 
     void attachPluginWindow()
@@ -1622,8 +1602,8 @@ private:
 
             if (scaleInterface != nullptr)
                 scaleInterface->setContentScaleFactor ((Steinberg::IPlugViewContentScaleSupport::ScaleFactor) nativeScaleFactor);
-
-            componentMovedOrResized (true, true);
+            else
+                resizeToFit();
         }
     }
 
@@ -1651,22 +1631,19 @@ private:
         JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ChildComponent)
     };
 
-    Point<int> getPluginWindowTopLeft()
+    void setPluginWindowPos (ViewRect rect)
     {
         if (auto* topComp = getTopLevelComponent())
-            return (topComp->getLocalPoint (this, Point<int>()) * nativeScaleFactor).roundToInt();
-
-        return {};
-    }
+        {
+            auto pos = (topComp->getLocalPoint (this, Point<int>()) * nativeScaleFactor).roundToInt();
 
-    void setPluginWindowPos (Rectangle<int> rect, int extraFlags)
-    {
-        ScopedThreadDPIAwarenessSetter threadDpiAwarenessSetter { pluginHandle };
+            ScopedThreadDPIAwarenessSetter threadDpiAwarenessSetter { pluginHandle };
 
-        SetWindowPos (pluginHandle, nullptr,
-                      rect.getX(), rect.getY(),
-                      rect.getWidth(), rect.getHeight(),
-                      extraFlags | (isVisible() ? SWP_SHOWWINDOW : SWP_HIDEWINDOW));
+            SetWindowPos (pluginHandle, nullptr,
+                          pos.x, pos.y,
+                          rect.getWidth(), rect.getHeight(),
+                          isVisible() ? SWP_SHOWWINDOW : SWP_HIDEWINDOW);
+        }
     }
 
     ChildComponent embeddedComponent;