Improve smoothness of dialog show/hide

Author: timothyschoen

Source/NVGSurface.cpp

@@ -169,6 +169,9 @@ void NVGSurface::updateWindowContextVisibility()
 
     isRenderingThroughImage = renderThroughImage;
 
+    // Render a frame to the new target before showing/hiding GPU context
+    renderAll();
+    
 #ifdef NANOVG_GL_IMPLEMENTATION
     if (glContext)
         glContext->setVisible(!renderThroughImage);
@@ -177,7 +180,7 @@ void NVGSurface::updateWindowContextVisibility()
         OSUtils::MTLSetVisible(view, !renderThroughImage);
     }
 #endif
-    
+            
     invalidateAll();
 }
 
@@ -476,7 +479,7 @@ void NVGSurface::setRenderThroughImage(bool const shouldRenderThroughImage)
 {
     renderThroughImage = shouldRenderThroughImage;
     backupImageComponent.setVisible(shouldRenderThroughImage);
-    if(renderThroughImage) updateWindowContextVisibility();
+    //if(renderThroughImage) updateWindowContextVisibility();
 }
 
 NVGSurface* NVGSurface::getSurfaceForContext(NVGcontext* nvg)