--- a/src/MacSrc/OpenGL.cc
+++ b/src/MacSrc/OpenGL.cc
@@ -332,6 +332,21 @@
 
     int width, height;
     SDL_GetWindowSize(window, &width, &height);
+#ifdef __ANDROID__
+    // Temporary diagnostic: the reported panel/surface size is correct
+    // (confirmed via SDLSurface's own "Window size" log and a Java-side
+    // onSizeChanged() probe showing no later relayout), but the rendered
+    // content still only fills a small corner of it. That means the
+    // divergence is somewhere below the Java/Activity layer - between what
+    // SDL_GetWindowSize() (the value used for opengl_resize() below) reports
+    // and what SDL/EGL/gl4es actually believe the live drawable size is.
+    // Compare all three directly instead of guessing further.
+    int drawable_w, drawable_h, output_w, output_h;
+    SDL_GL_GetDrawableSize(window, &drawable_w, &drawable_h);
+    SDL_GetRendererOutputSize(renderer, &output_w, &output_h);
+    INFO("Android size diag: SDL_GetWindowSize=%dx%d SDL_GL_GetDrawableSize=%dx%d SDL_GetRendererOutputSize=%dx%d",
+         width, height, drawable_w, drawable_h, output_w, output_h);
+#endif
     opengl_resize(width, height);
 
     // Now make the palettes
