added GPUDevice::WaitIdle function.

example/common/VulkanAppFramework.h

@@ -327,6 +327,8 @@ public:
         if(win->IsVisible())
             Draw();
 
+        device->WaitIdle();
+
         return(true);
     }
 };//class VulkanApplicationFramework

inc/hgl/graph/VKDevice.h

@@ -96,6 +96,8 @@ public:
 
     const       VkExtent2D &        GetSwapchainSize    ()const {return swapchainRT->GetExtent();}
 
+                void                WaitIdle            ()const {vkDeviceWaitIdle(attr->device);}
+
 public:
 
                 bool                Resize              (const VkExtent2D &);