internal rendering renders alpha channel

ui/renderthread.cpp

@@ -144,10 +144,9 @@ void RenderThread::run() {
 void RenderThread::paint() {
 	glLoadIdentity();
 
-	glClearColor(0, 0, 0, 1);
+    glClearColor(0.0, 0.0, 0.0, 0.0);
 	glClear(GL_COLOR_BUFFER_BIT);
 
-	glClearColor(0, 0, 0, 0);
 	glMatrixMode(GL_MODELVIEW);
 
 	glEnable(GL_TEXTURE_2D);

ui/viewerwidget.cpp

@@ -567,7 +567,7 @@ void ViewerWidget::paintGL() {
 		makeCurrent();
 
 		// clear to solid black
-		glClearColor(0.0, 0.0, 0.0, 0.0);
+        glClearColor(0.0, 0.0, 0.0, 1.0);
 		glClear(GL_COLOR_BUFFER_BIT);
 
 		// set color multipler to straight white