Btw, you have a ton of hints and warnings in your code, most of which seem to stem from not using the "override;" keyword on your Destroy method in you classes. I know this may not be a priority, but cleaning these H&Ws up will help you track down bugs more easily later on.
- yes. because it's from WIn32 version rewrited, now it's my first priority - clean up code

A bug I noticed when playing with the demo is that on the sound slider, if you change it's position then move the Window, the slider jumps a few pixels in the -Y direction.
- oops. it's a bug.


Also the depth setting of the spinning logo seems a bit odd as it on top of everything nor is it below everything, but maybe this was intentional.

GUI is drawed inside APP_RENDER_2D fnc and Hud is drawed at end of APP_DO_RENDER. That's all. Isn't a bug. If is neede change it so:

[pascal]procedure APP_RENDER_2D();
begin

F3D.Hud.SetFontColor('fixedsys',SetColor4f(1,1,1,1 ));
F3D.Hud.Print('Impact', 0, 0, 'Final3D® Engine 2007 - ver. 0.09');

F3D.Hud.ImageList.Image[SMALL_LOGO_ID].Angle := F3D.Hud.ImageList.Image[SMALL_LOGO_ID].Angle+(F3D.Timer.GetElapsedTime);


F3D.Viewport.DrawInfo(F3D.Config.r_viewport_width - 272, F3D.Config.r_viewport_height - 128 - 14;
F3D.InputControl.ShowInfo(F3D.Config.r_viewport_wi dth - 272, F3D.Config.r_viewport_height - 128 - 84);
F3D.Cameras.DrawInfo(0, F3D.Config.r_viewport_width - 272, F3D.Config.r_viewport_height - 12;

F3D.Hud.ImageList.Render();
F3D.GUI.Render();

end;


procedure APP_DO_RENDER();
begin

F3D.Timer.Update();

F3D.Viewport.Clear(0.5,0.5,0.5,1);
F3D.Viewport.BeginRender3D();

// .... 3D SCENE code here .................................................. .

APP_RENDER_3D();

// .... 3D SCENE code here ..............................................[END]
F3D.Textures.InActiveLayers();
F3D.Viewport.EndRender3D();
F3D.Viewport.BeginRender2D();
// .... 2D SCENE code here .................................................. .

APP_RENDER_2D();

// .... 2D SCENE code here ..............................................[END]

F3D.Viewport.EndRender2D();
F3D.Viewport.Flip();
end;[/pascal]