adjustments to control and stack saving

apps/LoopThroughWithOpenGLCompositing/gl/OpenGLComposite.h

@@ -44,7 +44,7 @@ public:
 	bool InitVideoIO();
 	bool Start();
 	bool Stop();
-	bool ReloadShader();
+	bool ReloadShader(bool preserveFeedbackState = false);
 	std::string GetRuntimeStateJson() const;
 	bool AddLayer(const std::string& shaderId, std::string& error);
 	bool RemoveLayer(const std::string& layerId, std::string& error);
@@ -110,6 +110,7 @@ private:
 	std::atomic<bool>						mUseCommittedLayerStates;
 	std::atomic<bool>						mScreenshotRequested;
 	std::chrono::steady_clock::time_point	mLastPreviewPresentTime;
+	bool									mPreserveFeedbackOnNextShaderBuild = false;
 
 	bool InitOpenGLState();
 	void renderEffect();