Fixed issue #1103.

src/org/nschmidt/ldparteditor/data/GL33ModelRenderer.java

@@ -2277,6 +2277,10 @@ private void renderThread() {
         idCount.set(0);
     }
 
+    public void stop() {
+        isRunning.set(false);
+    }
+
     public void dispose() {
         isRunning.set(false);
         GL30.glDeleteVertexArrays(vao);

src/org/nschmidt/ldparteditor/data/GL33ModelRendererLDrawStandard.java

@@ -1237,6 +1237,10 @@ private void renderThread() {
         idCount.set(0);
     }
 
+    public void stop() {
+        isRunning.set(false);
+    }
+
     public void dispose() {
         isRunning.set(false);
         GL30.glDeleteVertexArrays(vao);

src/org/nschmidt/ldparteditor/helper/composite3d/Composite3DModifier.java

@@ -365,8 +365,9 @@ public void closeView() {
                 }
             }
 
-            GLCanvas canvas = c3d.getCanvas();
             OpenGLRenderer renderer = c3d.getRenderer();
+            renderer.stop();
+            GLCanvas canvas = c3d.getCanvas();
             if (!canvas.isCurrent()) {
                 canvas.setCurrent();
                 GL.setCapabilities(c3d.getCapabilities());

src/org/nschmidt/ldparteditor/opengl/OpenGLRenderer.java

@@ -33,6 +33,7 @@ public abstract class OpenGLRenderer {
     protected final Composite3D c3d;
 
     public abstract Composite3D getC3D();
+    public abstract void stop();
     public abstract void dispose();
     public abstract void init();
     public abstract void drawScene();

src/org/nschmidt/ldparteditor/opengl/OpenGLRenderer20.java

@@ -2484,6 +2484,11 @@ private void drawGrid3D(float gridSize, final float gridSize10, final float grid
         GL11.glEnd();
     }
 
+    @Override
+    public void stop() {
+        // Do nothing.
+    }
+
     @Override
     public void dispose() {
         GL20.glUseProgram(0);

src/org/nschmidt/ldparteditor/opengl/OpenGLRenderer33.java

@@ -1975,6 +1975,13 @@ private void drawGrid3D(float gridSize, final float gridSize10, final float grid
         helper.drawLinesRGBgeneral(grid);
     }
 
+    @Override
+    public void stop() {
+        // Stop the renderers.
+        modelRenderer.stop();
+        modelRendererLDrawStandard.stop();
+    }
+
     @Override
     public void dispose() {
         // Properly de-allocate all resources once they've outlived their purpose

src/org/nschmidt/ldparteditor/shell/editor3d/Editor3DWindow.java

@@ -2344,6 +2344,9 @@ protected void handleShellCloseEvent() {
 
         // NEVER DELETE THIS!
         final int s = renders.size();
+        for (int i = 0; i < s; i++) {
+            renders.get(i).stop();
+        }
         for (int i = 0; i < s; i++) {
             try {
                 GLCanvas canvas = canvasList.get(i);